I was there with my band in 1990 for Magic Music Days. We marched at the MK, and also at Sea World. It was soooo hot at Sea World, really miserable...and us in our wool uniforms! We had fun at WDW, but after the Sea World parade, we were so hot that we just sat around there the rest of the day. Of course, there is much more to do there (Sea World) now than there was at that time... I know we spent an entire day at MK, and then I think the day we marched at MK we later went to Epcot and stayed until closing. We went to MGM (had just opened, as I recall) for a half day before coming home.
I don't recall where we stayed, maybe a Days Inn? Seems that now lots of school groups stay at the All Star Resorts (those weren't around way back when, either!). When we were there in April, there was actually a band playing (practicing) at 10:30 at night (All Star Movies). DH and I were both band nerds, but we were a bit perturbed to have that kind of disturbance~it was hard enough to get DS to bed as it was!