We just spent two weeks in Chiang Mai, last year we stayed at the Blue House...the fan didn't work, bed bugs and it was noisy. The last two years our place of choice has been Mountain View, inside the moat, across from Chiang Puak Gate. Clean, friendly, cheap, good restaurant, with a roof top terrace, plus if you like street food the best night carts are across the street, most of the locals seem to gather here so you know it is great. All of the sawngtheaws and tuktuks also know of mountain view so its easy to get there from any part of the city. Rooms start at 200 to 250 (prices as of Aug09) ask for the rooms off the street or over looking the garden; not on the street side as those are often noisier.
Have a great trip .....oh and if you need a good dentist go to Grace!