Yeah, hi. Really depends what you are looking for. In my opinion, Khao San Road is way overcooked. It is a backpacker ghetto. It is also well isolated - close to the Royal Palace and other important and interesting cultural locations, and close to the river, but well away from the Skytrain/Subway and major shopping areas and markets.
Your accommodation choices are going to depend on your budget, essentially. Khao San Road area is often choc-a-bloc, 24-7, and you might have to do some serious and sweaty searching to find anywhere at all to stay - even somewhere you find far from ideal to your tastes. And it is not really cheap anymore.
As to Suk 11, with the deepest respect to other forumites, I went there to have a look and was not impressed. And for those rates, you can stay at a quite decent hotel in the immediate area.
Having said all that, the Khao San Road circus is worth a visit. The market stall prices are competitive. (And there is a fantastic Korean seafood place worth the taxi fare.
I have stayed around there in the past, but I now believe there are better options. I wouldn't stay there again.
More than happy to answer any other questions.
Whatever you decide - enjoy!