The first thing you should consider when punting abroad is that not every hotel is "girl friendly".
That does not mean you will not be allowed to take a girl back to your room but they will "fine you" .
Booking a double room will not avoid this problem as some hotels charge for an "unregistered guest", yes it is a rip off but it is common in many countries from Bulgaria to Thailand.
My advice is to either get a recommendation from other punters or else send the hotel an E-Mail asking if they charge for unregistered guests and take a copy of their reply with you as proof.
In Bangkok this group of hotels allow guests with no surcharge -------(small charge for 2 girls)http://www.dynastyinn.com