Hey-
I'm just a little confused based on your wording. You definately need to call your EM or the catering and event staff to be sure they know it's a rehearsal dinner. If you don't and try to book, Disney cannot and will not guarentee that you will be on the first floor near the pool. Whereas if you're working with someone on planning the event, you're a lot more likely to get what you want.
I don't know your budget, but dessert parties at the Grand Floridian marina are not that much. PM me if you wanted the cost breakdown of our's. We did switch over to the California Grill becuase our inclement weather plan was not a plan as far as we were concerned... we would have been in a Salon room with background music.
When I had posted about alternatives for the dessert party at the marina, someone had offered the idea of using one of the suites at the Grand Floridian. I believe she said it was the Coral Suite, is ground level with a direct view of the Magic Kingdom, and had a bar within it. We were too large a group at 36 to use it, but it could work for you. Additionally, some of the other resorts may have such accomodations available. I am not sure what the usage fees would be.
If you stayed at the the villas, you could have a really fun, low cost pool party rehearsal "dinner." You could send outr fun and cute invitations that have bathing suits, beach towels, and beach balls, that sort of thing. A few tray like a vegetable tray, cheese tray, sandwich tray, and a fun dessert could do just the trick. You could even look into using a local supermarket to supply the trays. Goodings is located right acorss the street from DTD Market Place in the Crossroads shopping center. You might even find cheap beach towels to give to your guests.
Hope this helps!
xoxo
PS- I am assuming your having a summer or spring wedding and it's warm enoguh to use the pool!