We always tip the housekeepers, daily. I put a post it note on top with a 'thank you,' so they know it's for them and not just money we forgot to take with us. When Sunny (our pup) is with us, a little extra is included from her. Our second hotel in London this year had a can on the check in shelf for staff tips, so the one exception to our daily tip. I stuffed it in the can when we checked out.

Cheers and happy traveling,

Peggy