In my experience most limited service brands that are part of the Marriott and Hilton tend to have guest laundry rooms. Sometimes they are tucked away on a upper floor as opposed to be down near the lobby. Some even have complimentary detergent. I think the ones that complimentary detergent probably have HE washers so they want to make sure you have the right detergent.

If you are a frequent enough guest and spend too much time at the the hotel bar. The manager might just let you do your laundry using the housekeeping facilities.

I would certainly hope any brand/place that markets itself as an extended stay property has guest laundry.