One night, my husband was gone til late, and I was tired. Of course, the kids wanted to do something. They came up with an idea on their own (great!). They decided (and agreed!) that they would get their instruments and play all the songs they knew from memory. They allowed each other some time to go over music, then put it away. I was a wonderful audience-I laid on the couch and enjoyed all the wonderful music! This works well for big kids, but if your kids are little, you can still have a music fest they will love.
Simply allow them to put on a show for you (or join in with them) using what ever "instruments" they can find or create.
If no one in your family seems inclinded to play an instrument, put on some great music and dance around to it. Another option I used to let my kids do (when still small enough) was to pile the couch cusions on the floor and jump on them while listening to music. It's like jumping on the couch without really jumping on the couch!
Your family can find its own way to make beautiful music together.