Great thread. We cut back a lot in the last year or so due to dd7's recent need for vision therapy, and I am very reluctant to get her back into dance, in particular. It is a wonderful opportunity, absolutely, however with classes added to performances, and practice for performances (eg: nutcracker) it just adds up to several days a week and full saturdays very very quickly.
Tae kwon do was this way too; medium to large weekly commitment and year round with almost no breaks makes it something we are taking a break on until the kids are much older.
It's hard when you have your child in ballet to say, no we can't also do tap. Or, no, we can't commit to sleeping beauty, when it seems to her like ALL the other kids are doing it. But now I think she recognizes that the ballet thing was mainly to get some time on stage and that there are other ways to do that as well, and we are remaining firm on limiting all activities to a couple days a week.
Non-year round activities really help with being able to pick something new. Thankfully our rec soccer league here is very much oriented that way, so it is a good fit.
I mean if one of our children shows a real desire to master a sport, to the point of even practicing, stretching, reading about it a bunch at home, etc., then we might consider committing more, but otherwise we are keeping it fun and light.