With our older kids, we encouraged them to do SOMETHING, be it a theatre show, a sport, a hobby. At least one thing a year. If they really got into it, they might do it longer. If not, it's one show, one semester, one year. Enough that they got an experience, but not so much that they were drowning in "requirements".
You also need to balance other things, like family activities, school load (AP students have a LOT on their plates), etc. I think some families get too caught up in making sure that Johnny and Suzie do 15 things a piece and no one has time to breathe and just "be". Not everything needs to be organized, scheduled, and scripted. Friends of ours also toss schedules out the window if it's been a bad week. Sometimes it's best to go, "Okay, maybe we won't do x tonight. We'll just stay home." Just because Suzie plays 3 sports and Johnny speaks 4 languages doesn't mean they're any better than another kid.
The question also becomes - is it for THEM, or is it for YOU? Are YOU trying to live vicariously or is it really something worthwhile for them to do?
I do a few things a week with my small child - a play date, a special event, the library, the nature center (not usually all in one week). Things that give her/us an opportunity to get out of the house but not so much that we feel oppressed by them. I do enough that she's socialized and has new experiences and learns something I might not have thought to show her.
And other times I just let her stick crayons in play dough.