I was 14 the first time I saw RENT (mature for my age though I was, I still love it, and I've seen it with 14 year-olds before) and I think it would be great to see with your kids, especially before it closes. RENT is an amazing show and an amazing experience.
Other than that, Hairspray is a blast and the other suggestions are good as well. I too would, however, probably nix Spring Awakening not because your kids couldn't handle it, but because I too (almsost 18, here, and very close to my mom) feel it would be awkward to see with a parent. You can ask them.
Have fun!
Measure your life in love, RENTheads, and keep it always in your heart.
Avatar: Me with Al Larson, Jonathan Larson's father.