If you are fit you can do it in 15-20 minutes. There are nice shops and cafes and massage all along the road, so for a one night stay it is good. Silom Village is a nice place to look around, and you can walk to the Chao Phrya river in 20 mins too. I am loyalty member and got a free night and a free beer. You should be able to get a hotel room for about 2000b RO; the rooms are really nice. You can always take a motorbike or taxi to Patpong if it is too hot to walk.