First and foremost, kids are fickle. Don't worry! For reasons I cannot
imagine, things can change, and change they do. What is so 'in' one
year is definitely 'out' the next. Right now our band is tiny, but next
year, who knows.
The team/social/band aspect of music sounds to me like what you are
dealing with. It is fun to do cooperative music and yields a team
feeling in most settings. I don't know that we art instructors
absolutely have to do team projects, but it is a different mode of
teaching that may appeal to some kids. Some of my HS students recently
did a mural on 'community impact' day, and it was something to rally
around as an art 'team' effort. They had a lot of fun.
The cooperative events we have done are few and far between but really
make an impression. We installed a fibonocci spiral line made of
bushels of 1"seed pods from a sweetgum tree. Kind of a math
interdisciplinary thing with Andy Goldsworthy overtones. Very brief
'show' but we still enjoy the photos and memories.
You could always do one of those huge grid drawings with each student
doing a single large square. If you are a little burned out, I have
found this to be a lesson that required little of me and yet the
students enjoyed. We did the Mona Lisa or other famous imagery. A
six-foot image of her in your cafeteria might make a big impact if you
save her for the cafeteria next year the day before the art show!