Hilton is good. But refer to some Chings' reports, we need to pay extra to the hotel for taking overnight girl, this make me tick Hilton out from my list...... Anyway, Ching, thanks for your great report.
If you bring the girl in before 2200 hours (before shopping mall close by entering via mall lift lobby to hotel floor), it is free. After mall close, you'll have to enter thru' hotel entrance and you are subjected to 1000 baht registration. Guess that is a cost budget you'll have to suffer for a good accommodation.