I go to Bangkok, Thailand quite often due to my work. I usually use the service from www.silkzpider.com
because they have the hotel room listed by location.
This site offers hotel online reservation service for Thailand hotels and accommodations. From the home page, they also have the search box on the top left hand side for us to put down the information such as location, star rating, max and min prices. They do offer the hotel, guest house, motels in Khao San Road area.
I love it because you can pick the price before getting to the detail of each hotel. Remember, the higher the room rate, the better the service. It has taught me so many lessons. I usually pick the lower room rate when I go there alone, and pick the higher room rate when my wife go with me.
From my experience, I recommend Viengtai Hotel Bangkok
because it is cleaner and offers better service. Each hotel has the section called "Traveler Reviews". You can get insight info from others, too. The hotels that I already stayed are:
Pathumwan Princess Hotel Bangkok
= near Siam area and close to major shopping area
Banyan Tree Bangkok
= located in the business district
Four Seasons Hotel Bangkok
= near Pratunam area and close to shopping area
= located in the business disctrict area
Novotel Siam Square Bangkok
= in Siam area, closed to shopping malls and Hard Rock Cafe
Viengtai Hotel Bangkok
= in Khaosan area and enjoy the clubs along this road
Wishing you to have great days in Thailand - the land of smile : )