Tipping hotel cleaning staff is appropriate and can pay off. Last summer in Vegas I tipped a five-spot on the first morning, the cleaning lady left one of the new irons and ironing boards, a large stack of extra towels, and a huge bag full of soaps and shampoos (the stuff literally lasted me for months).
I don't always do it if I'm in the place for just one night, but if you're there for a few days it could be a benefit for you.

