Recess Monkey. The trio of teachers from Seattle is a great find. My kids love the silly but not stupid songs and I do too. I really didn't see myself rocking out to songs like 'Grandma' but then we went to a Recess Monkey show at Wolf Trap's Theatre-in-the-Woods and I did just that. So did my two youngest girls too.
While it was a not so enjoyable heat scorcher of a day we braved the elements to see this band and it was worth it. They are fun, not too loud, and full of energy. The whole audience of kids and parents had a great time dancing, singing and acting out songs. My 11 month-old could not stop waving her arms and moving to the music, something I had never seen her do before. I highly recommend seeing Recess Monkey at least once.
Wolf Trap's Theatre-in-the-Woods is a wonderful way to introduce your kids to concerts, plays and puppet shows. The venue is not too big and it is a fairly free feeling setting. You can picnic nearby and there are ample bathrooms. There is also a good amount of staff on hand to answer questions and just help out.
If you are in the Washington, DC area it is a great place to take your family but also a night out just for adults.