I can answer about the VMI band. It's a separate company like the rest of the corps, but it also functions as a club. It has the regimental band which is mainly the brass, and the pipe band in the Band Company. Both bands have percussions. If your DS is already a percussionist, the regimental band probably will work better. The regimental band director, Colonel Brodie is a really good guy and everyone love him. The pipe band is also good by nature since people like fancy bagpipes and kilts. It's also fun to learn a different culture in the pipe band. There is more information on the VMI website.
However, there are some truths that I think I need to let you know. Many cadets don't like Band Company, both cadets in the band and cadets not in the band. There are various reasons. For example, Band company is different than everyone else since cadets are drawn by musical abilities but not by heights like everyone else; the Band parades with instruments instead of rifles and that's "easy"; the Band rats have lower requirements than other rats during the ratline (a little bit, especially the rifle drill part but not too much); the Band gets on trips to different places that everyone else want to get on; some Band kids are weird (VMI cadets are all weird?) and have some other stories (you will figure out if you actually come here). People hate the pipe band a little less than the regimental band since pipe band sounds better than the regimental band and pipe band is cool. In my opinion, if your goal is to become an Army Ranger or a Marine, probably not Band because people are going to laugh at you and say you are weak, and you will have more time to focus on the military instead of band practice and parades. Otherwise, Band is still a good place to have great opportunities, both learning new things and getting out of VMI and have some fun.
I hope that helps.