Kawin Place, behind the big Irish pub (yeah I know) in middle of Khao San Road, is very nice. Its only about 300b for a spotless clean twin room and has hot showers. Plus it is near everything and the staff are nice. And when I say clean I mean it. Its set in two buildings, and there's balsoanother place in one of the buildings, which is the same price and just as good.
I recommend the new visitors to BKK to stay near Sukhumvit Road where all services and entertainments for tourists. There are many deferent kinds of hotels on price range from 400 BHT to 3000 BHT. However, i recommend people to look for a hotel around soi 3 to 11. Last time i booked on Business Inn Hotel which located on soi 11 and it can fit everyone budget. The old building only 500 bht the new one around 1000 bht. Try this link the most popular one you will find it very useful and you can read travellers comments on each hotel www.sawadee.com