I'm not sure why I find this thread so fascinating!
We are pretty "green" in most ways - recycle, use "green" products to clean the house, etc., etc. but I am realizing we are totally the opposite of green when it comes to towels.
We have a ton of towels. All the Winnie-the-Pooh towels are my dd's. She also has some older towels that used to be dh's and mine as back-ups. She uses two clean towels every bath or shower and then they go in the hamper. My dh and I have a stack of towels and every shower we take a clean one off the top of the stack and put it in the hamper when we are through.
We share hand towels, but I change the hand towel in my bathroom almost daily. I'm not sure how often dh changes the towel in the downstairs bathroom or dd's bathroom, but it is a least once a week.