I was in the same boat as you all, I was a young adult (still young, im 27 now) for my first trip too. Since then I've been 8 times in the past 4 years, mostly going with just my fiancé and myself.
How long will your stay be as in actual days in the parks?
My biggest advice is to do your research, figure out what are going to be your "must do's" rides and/or shows, figure out what restaurants you want to eat at also. Familiarize yourself with the new system Disney World is using, My Magic Plus now before you trip. Incase you don't know already you can make reservations at sit down restaurants starting at 180 days from your check in date, you can also book rides too (just not 180 days out, I think 30 for rides/shows). Since you will have a decent size party, is it just a group of friends or do you have couples going too? If so they might want to plan a night to themselves. Besides the parks, I like to do an evening at Downtown Disney which they are in the process of transforming into Disney Springs. By next fall a lot of the work will be done so if you all like to shop you can plan a half day down there.
My second piece of advice is DONT RUSH, take your time and enjoy the theming of the parks. I know families that plan their trips to the minute and IMO it just seems like another day at the office and not a vacation.
As far as your resort, I'd expect a lot of families to be there since Art of Animation is Disney Worlds newest resort and the price is on the low end. If you can spend a little more per night I'd highly suggest upgrading to Port Orleans French Quarter. It's a much smaller resort, shouldn't have as many screaming kids running around and you get a very small taste of New Orleans (where I live) without the crime rate hahaha.
Also, if you or some of your group likes to drink a few adult beverages, look into "Drinking around the world" in Epcot. You'll thank me later lol.
Most of all though, have fun and don't stress. Keep us updated if you have any specific questions. Searching and asking this forum alone will make your trip better!