Ghost rider, is this the one in Universal Studios?  If so, you'll have to let us know if it's good and worth the admission price.

Hello,
I have some information for you as I'm a bit of a theme park enthusiast: I will be visiting in April, but I've read up on things so I'm ready. So, I'll give you some info below and my thoughts, although I'm speaking as someone who hasn't been but who has read:
I'll start by telling you what you are actually in for, without trying to spoil too much for you though, this post is going to be a little long and should get you excited:
The wizarding world is split across two different parks, both of the universal ones now. Diagon alley is located in universal studios, the main attractions are escape from gringotts, and the hogwarts expresss, more on that in a second.
In Islands of Adventure, you've got hogsmeed. The attractions are Forbidden Journey, located in Hogwarts Castle, and Dragon Challenge, a roller coaster based on the triwizard tournament.
Now, for some general tips:
First, get there early. It will probably get crowded. Start your day in one of the wizarding world areas.
When you first get there into one of the wizarding areas, head for the main rides and attractions first. Then, explore the rest of the universal parks as they have lots of other attractions to offer during the day, stuff like marvel, mummy, men in black, simpsons, e.t, etc, depending on what park you are in. In universal studios there's despicable me and springfield based on simpsons, men in black, in islands of adventure there's marvel superhero island, jurassic park, toon laggoon and an area based on doctor seus. Then, at night, go back to wizarding world and explore the land for it's atmosphere and details if you have someone sighted with you make sure they describe everything to you. That way it won't be so busy at night and you can get in re-rides of the attractions a little easier.
Make sure you have a park to park ticket otherwise you will not be able to ride the hogwarts express, from diagon alley to hogsmeed and back again. This goes from universal studios to Islands of Adventure but keeps you in the harry potter story and everyone's saying that the sounds are quite good.
I would seriously recommend starting where harry himself started: diagon alley.
Diagon Alley has an area before it calld London Waterfront, which actually hides the area. It's a sort of prologue into your experience. There are stands around, and if you are lucky there may be London inspired performers too.
Once in Diagon Alley (any prospective wizard, i.e: reader of the books or watcher of films, knows how to get in), visually, you are going to notice that not everything is shown. When you take your first few steps, however, everything's going to fall into scale and Gringotts will come into view, way down the street. This is definitely where someone sighted will help you. You will want to stick around outside the streets as there is an effect that happens on the Gringotts building, and it is noisy.
I hope you have cash on you, because if you do you might want to go to Ollivanders and pick up an interactive wand, assuming there's someone to help you. I think these are around 40 dollars but don't quote me.
As you do this there's also a little show in Ollivanders you can enjoy. Once in the store make sure to ask for an interactive one.
The interactive wands will let you trigger events round both wizarding worlds (yep, even hogsmeed), and there will be staff stationed at each area to help you do this. These events also make sounds.
I'd next make a bealine for Gringotts. The queue here can be pretty massive, but you can roam around and explore. Also, I have heard this from Warrek Davis (a.k.a: the voice of Griphook the goblin,) himself: anything not behind a barrier, can be touched.
Gringotts also has a ride portion, the less I say about it though, the less you will be spoiled, but if ou can handle it, I recommend you go for it. It does not go upside down.
Diagon Alley is split into three sections: The alley itself, Karket Market and Nocturn Alley.
In Karket Market, there are some shows that take place: one of them is musical, the other is story-based. I don't know how to find out times for these shows though.
Nocturn Alley has a lot of interactive wand segments.
There are lots of foods to try too, and of course butterbeer. I plan to try this when I go.
Hogsmeed doesn't ned much describing and seems to be more straightforward an area compared to the rather large in scale diagon alley (people have stayed there for hours at a time but that's because of it's visual details, although there is audio too).
I hope you enjoy yourself, and please let us know how it went when you get back! Also enjoy the rest of the parks too, don't just stick to potter unless that's all you really want to do. Remember you are in universal so the hole of that area is at your leasure.

There are some DC-themed rides at Six Flags (They sorta license WB, and WB licenses DC), but they're nowhere near as atmospheric as Disney and Universal.

Hello,
I've got some other thoughts on theme parks below, I'm loving this topic!
@brad: I also live in the UK. I don't know if I'll post any vids that are currently out there, I could do this under a spoiler tag, but if Ghost Rider is going next week I don't really want to post anything yet, for my reasoning, see the question below.
@ghost rider: this might be a longshot, but will you be taking any sort of recorder? It could be interesting if you could... maybe... get some audio, for people who can't make it anytime soon like brad. I actually don't mind spoilers, in fact that just makes me more hyped. Now, you'll have to be a bit careful, but if you have a tight enough pocket with a zip you might be able to zip it up even on stuff that goes upside down. If you keep it in an unzipped pocket they will probably ask you to put it in the lockers, as it'll be considered a loose article. If it's zipped up though, you might get lucky.
For the rest of us though, will you get to do a text report? If so, I've got some questions, although I don't know how easy they'd be to answer because it might be a bit of a blur:
If you get to universal studios, could you please try riding Transformers if you ahve time and let me know your thoughts, as I'm also interested in that and am wondering how much the ride moves around. Same with Gringotts in the harry potter world. I know it doesn't go upside down, but is it fast? how sudden does stuff happen?
Also... although I'm a theme park enthusiast, I'm a bit scared of the following rides:
Park name: Universal Islands of Adventure:
Ride name: Incredible hulk coaster
reasoning: unsure of the unknown, for those who know what happens does your stomach go a heck of a lot or will it just be such a blur?
ride name: Doctor Doom's Fearfall
reason: once up the top, how long do you wait before dropping? is it random?
park name: Disney's hollywood studios:
ride name: tower of terror
reasoning: I've heard the thing drops a lot, but I've also heard that it's always the same duration. I'm not sure how to conquer these fears. I could just say no, but then when I fly home I'm worried I'm going to regret it big time, as I didn't ride it. Does anyone have any tips on how to go for conquering a fear, and if it's worth trying to do that?
I know hat tower of terror has a lot of atmospherics too so if I don't o that I'll probabl miss out on all of that good stuff.

Hi.

You could always tell us what to type into youtube for example. Then there would be no spoilers.

As for fears. Hmm  maybe imagine you're tummy doesn't exist... But that could kind of sort of, not work... Lol I'm silly. I don't know how to help with that since I've not had those kind of fears. I have a kind of fear of eletric shock machines and toys and scary horror mazes that have nasty horrible, not nice at all, people in them that do unspeakable things with shocky things that shock you... I'd totally not go in one of those places, not even if you paid me... Hmm well okay fine, I'd consider it.

@Aaron: It's hard to tell what your stomach tolerance is, but let me try:
The Incredible Hulk is awesome as coasters go. It sounds like you don't like rides that are too surprising, though, and the first time might be a bit surprising, especially toward the beginning. Get past that and it's mostly just a coaster.
I didn't ride Dr. Doom, because at the time, I was avoiding Tower of Terror-esque rides. The reasoning had less to do with the Tower of Terror (even though it will always be my reference for the archetypical "giant drop" ride) and more with Space Shot at Huntsville Space Camp.
I rode Tower of Terror before the rest, and didn't have any problems with it--although I was kinda taken off guard by the second drop, it's changed since then. Space Shot gave me this feeling best described as "my internal organs are being forced out through my eye sockets", for which I avoided similar such rides for the next few years.
When I eventually rode the Tower of Terror again, the only stressful part was waiting for the first drop. After that, even the variation and pauses weren't so bad.

If you do come back to this topic, Ghost Rider, I'd really like to know what butterbeer tastes like. I've been curious about that for some time.

I went to hp world and it was amazing. I didn't go on many rides, I kinda slmost freaked out a bit, but I did buy a wand. Not an interactive one, but I bought Mad-Eye Moody's wand. I also bought a box of Bertie Bott's Every Flavor Beans. I also bought my girlfriend a Snape Keychain, its a joke between us. I did go on the Transformers rid, it was really intense but I loved it. I went on the simpsons one and its hillarious. (My bosom's are hitting me in the face!) I love the butter beer, its best cold. If you go, have fun!