I usually leave about $2 per day and leave it on the table in the room on the day I checkout. If I’ve been particularly messy I might leave more…But now robhaya is making me feel cheap so maybe I’ll have to start leaving $5 per day! Hotel workers are treated pretty badly in many hotels, and barely make a living wage, so your tip really helps them. I’ve often found it strange that we tip bartenders or hotel doormen lots of money for really easy things like pouring a beer or opening a cab door, and yet many people don’t tip a maid that spends 15 minutes changing your dirty sheets and cleaning up your bathroom in your hotel!
If you are interested in helping hotel workers, there is a lot of information on this site by UNITE, a union that represents some hotel employees (although most are not unionized). http://www.hotelworkersrising.org/