They're all fun!
If you're a lady, the princess is a great first half. Fun course, you get to run through the castle, great theming and lots of first time half marathoners. (If you're a guy, maybe s little less fun).
The half during marathon weekend is almost the same course, and I've heard the atmosphere is great that weekend, and really runner focused.
I've never done the wine and dine half, but will let you know on 60 days how that is! It's different cause it's a night race, but I hear the after party is the best.
In general, you're right, the races ate filling incredibly fast, like you need to register as soon as it opens, which can be a little annoying as that's up to 8.months before the race.
Also, have you considered starting with a 5k or 10k and working your way up? I've only done one Disney 10k, but they might be even more fun as you sometimes get proportionately more time running in the parks.
Also, you don't have to run! You can walk them too, as long as you can maintain a 16 min/ mile pace.