Grand Watergate Hotel
 

No personal experience here but room rates for
period Sep thru to end December 2007 from 800baht a night to 1400bht depending on room.
free car park,free wi-fi, rates include 2 free American breakfasts.
Rooms seem small,from 20 sq mtr.

http://www.grandwatergate.com/index.html

Too far from any skytrain station so it's a taxi job if you want to go anywhere other than Pantip or Pratunam market.

still seems like a nice place and im sure its good for a few nights when you do your shopping, 1400 for thebest room seems like a bargain