Haikudude,
For sure there are short-time hotels in Chiang Mai.
If you've picked up a boy from a bar, he would know where to go, or at least the mamasan would be able to advise.
My favourite (I've used it twice, imagine that!) is a kitschy one north of the superhighway. It's called Love Boat, and it's built like a ship stranded in the midst of tropical jungle. The rooms are marine-themed.
Love Boat is shown on the map
Directions to Adam’s Apple and Lotus Hotel « Shamelessmack in Thailand and around
Beware though, it's so far off the road that you'll need a vehicle of your own. Getting a tuktuk from the Love Boat hotel may be impossible especially if late a night.