Khao San Road, Bangkok

Hi! I have been there several times. Lot's of foreigner or back packer get there and with silver wholesale.
If you are in the heart of Bangkok, you can easily to get the Taxi to get there. Taxi is not expensive especially if you are shared with people.
I know how to take the bus to get there but it seems not convenience for you as it has many route, take times and it depends on your location.
It is not reached by metro/underground or sky train. Also, Tuk Tuk(kind of 3-wheel cycle vehicle) as it inot recommended as it is a long way for Tuk Tuk.

So I suggest to get a Taxi and remember to asked to meter counted. Save time, not expensive and you can really get to the location while in Bangkok.