I typically do not tip for basic housekeeping services, as increased employee wages is always part of the justification when Disney and other high-brow lodging operations raise their rates, every year.
But then again, I typically do not stay at a Disney O&O resort* where, depsite what Disney corporate says about housekeepers being in a "non-tipping" position, some people are still going to do it simply because it has a cute nickname, and it's fun to make tip envelopes as part of the trip-planning process.
Now before I get flamed, I am just being realistic. Consider this -- does anyone here send-out tips to the cabin cleaning crew (read: dirty bathrooms) and the people who pump-out the toilets after your flight to/from MCO?
Ridiculous as it may sound, you could give a sealed envelope addressed to either crew and hand it to the gate services supervisor for your airline, as you board/disembark your plane.
IMHO, aircraft cleaners/lavatory service truck operators have a far dirtier job than any hotel housekeeper, and their pay is only about $10 an hour.
*CAVEATS - I normally stay at Shades of Green, where their staff are Non-Appropriated Fund employees (they are working for a government-run operation (in this case, the Army), but not being paid with our tax dollars - their wages come from the military's Morale, Welfare, and Recreation fund, of which I routinely contribute to in other ways).
As for my take on tipping, if someone in my party has created extraordinary circumstances which require what I would call a "non-routine" level of cleaning (for those of you with small kids, you can use your imagination on this one), I would then tip appropriately according to the degree of the mess we made.