[MrDK]

A few example of Hotels that I have stayed at of know for sure in Bangkok:
Majestic Suites, Dynasty Grande, Nana Hotel, JW Marriott, Majestic Grande, Dynasty Grande, but you will find that by far most hotels on Sukhumvit are GF (not all though). Once you narrow down your choice, send them an email and ask if you are allowed to bring a guest without paying joiner fee. If the email is affirmative and you book the hotel, print out a copy and bring it with you.

Many hotels do not have A joiner fee, however, if you bring more than one girl back there may be a small charge.

To read up on hotels you may also want to go to "Advanced Search" and search for Hotel and select Search Titles Only. You can even limit the search to a specific forum such as Bangkok or Pattaya.