I stayed for 3 weeks at the family-run Night Bazaar Suites Guest House, and I will probably go back next time.
I had a huge room with a king size bed, free wifi, fridge, sofa, coffee table, flat screen TV with all the usual channels, and en suite bathroom. The guest house is located in a quiet soi close to the night market and with only two or three rooms on each floor you don't hear much from the other guests either.
The only minor drawback I can think of is that there is no elevator, so book a room on the lower floors if you have heavy luggage. And there is no kitchen/restaurant at the guest house but there are several restaurants within a couple of blocks, both Thai, Italian and Japanese.More