I always prefer to stay on the river in BKK, so Hilton is an easy pick for me. It is a great place to escape the madness of the city, while still remaining in the heart of it all. I never tire of the view and watching the many boats going up and down all day/night long. The main tourist sites are all reachable via river ferries, which are very cheap and avoid the hellish traffic in town. Hilton also has a great breakfast spread and a lounge with a fantastic city/river view. Easy access to the rest of the city via the Saphan Taksin BTS station on the river (free regular ferry between the hotel and the station). The location of the Conrad is really only convenient for shopping malls and embassies.