First, congrats on your band making it! It's a real honor! I'm located near you...over by Carbondale, Illinois (SIU), so it's kinda like hometown proud!
At AK, you should go to the Kilamanjaro Safari as early as possible to see all the animals out on the savanah...and do Tough to Be a Bug...it's a hoot! Dinosaur is really good...and if you are into music, (Doh!) go see Festival of the Lion King...it is a fabulous show! A lot of people love Kali River Rapids especially if you don't mind getting soaked! Try to get Fastpasses when possible if the wait time is getting longer than you'd like to stand in line. Well, this will give you a start...I'm sure there are many others who can give you some more ideas!
Just out of curiousity...when will your band be at WDW and exactly when are you marching? As a band parent, I like to give the bands a show of support when I'm there...ya'll work harder than people think!
If you've got any more questions don't hesitate to ask them here at the DIS...it's a great source of information!!
Enjoy your trip!