Thanks for the feedback. I should probably start researching IoA more since I really do not know much of anything. How long will an average HP fan spend at that area? I am starting to think this may not even be a full day trip for us.
There is a lot to do at IoA. I walked into it a bit of a Disney snob, and walked away from IoA / Universal not only impressed, but actually wishing we'd spent a bit more time there than just 3 days.
As far as HP, it really depends on when in the year and when in the day you go. There are two rides. Dueling Dragons (which I did not get to do because my kid was too short last year), and Forbidden Journey. The wait for both these rides will generally be long, unless you do them right at park opening or right before park closing.
Expect 30+ minute waits for both rides, with 60 - 90 minutes not being out of the question at all. The good news about this is that Forbidden Journey (that's the ride inside Hogwarts) has hands down the best themed queue I have ever seen in my life. When the kid and I went, we didn't run into very long waits on the ride...which sortof bummed me out. I actually longed for a wait in the queue to I could soak in all the details and decor. So, if you see a long wait time posted, don't fret. Once you get inside, it will be worth every minute, and I'm sure you won't find yourself bored.
It's stunning...just stunning.
The shops tend to be crowded, especially Olivanders, where they do "wand selection" in the back. If you and your GF are raving HP fans, I would certainly suggest you make it a priority to do this event. However, it's crowded and there is another long wait here. The kid and I opted to skip it, and I was genuinely surprised when she didn't even want a wand.
The windows there are worth slowing down and observing.
There's a restaurant (the Three Broomsticks) that I've heard good things about, and walked through (also amazing theme, lots of hidden goodies that make references to the movie / book events), and the food looked pretty good. Butterbeer is sold at a cart in the middle of the courtyard out front. Try both the regular and frozen. I preferred the regular, the kid preferred the frozen! In either case, get it with the frothy cream on top. Yum!
The Hogwarts Express is off to the side, and the Conductor will come out for meet and greets. I may be mistaken, but as far as I know, this is the only Potter themed meet and greet / walkaround character you will find there.
Also, there is a postbox there where you can mail a postcard to yourself or a friend / family member and it will be postmarked "Hogsmead". Fun little thing to do! Also, don't forget to stop by and pick up a chocolate frog and some bernie botts every flavour jelly beans!
So, all that being said (and sorry, I didn't mean to go on so long), I would guess, including rides, eating and shopping, that it's about a 3 - 4 hour experience...5 if you stretch it out.
That being said, once you buy park admission to IoA, you may as well stay and make a day of it! There's lots of fun things to do. Jurrasic Park has an amazing playground (though to ride the Pteridactyls, I believe you have to have a kid with you...but that ride is awesome, and harrowing even to me in my mid 30s. Several times you feel like you are going to fall, it's awesome!). The River Adventure is worth doing, but I found it a little loud and underwhelming. Hulk and Dr. Dooms Drop are both amazing looking thrill rides that I didn't have a chance to do, as the kid is too short.
The Spierman ride is loads of fun. Not as good as Harry Potter, but a close second.
Ripsaw Falls is a true log flume that, as far as thrills, puts Splash Mountain to shame (splash beats it on theme and overall ridability however), and for a few quarters you can squirt people from the water guns mounted on the bridge...which, if you are a bit sadistic, is lots of fun.
Toon Lagoon has several fun things to do, including the Bilge Barge, which is a tube style water ride, and you will get soaked. Not wet. Soaked. It's awesome! The theme is pretty fun as well.
Seuss is probably not something you and the GF would be interested in, unless you grew up with the books. If you did, there's a lot of neat little things to see there. The details are tons of fun, from the Sneeches to the Lorax to the Zax, still standing, foot to foot, face to face.
Also, there is a very good restaurant there (near Harry Potter, actually) called Mythos. It's been rated one of the top theme park restaurants in Orlando, and I don't doubt that from what I saw. We peeked inside, but didn't have time to eat. The menu looked very good, as did the food being served. Also, I've heard rave reviews about it from people who have gone.
So, sorry to go off one such a long "summary", but it happened. Hope it helps!