I've traveled to Bangkok several times now, and I hope that you will be travelling alone. You are able to meet way more people on your own. Make sure that the hotel won't be charging you any fees for the girls that will be staying with you.
If you want a convenient and cheap place I would recommend Majestic Suites. 10 steps away is Nana Hotel and the nightclub inside is just awesome for picking up girls.
You should check out the WSG forum and read all about it. Have a good time and PLAY SAFE!!!