Yep... it's also nice to buy the host family a gift. I don't think it's right to try to get off cheaply... afterall you do want to be invited back. Why do people not always get this?

If I had to ask a family to help out I would but I guess i wouldn't push it.... but I would NEVER invite them back.

ETA: Yep, I like Bron's suggestion of closed choices regarding the cleaning.