I stayed at the Adelphi Suites a little over a year ago, so this info may be dated...
Adelphi is GF, however they charge a joiner fee if you bring more than 1 guest at a time. I think the price was 800 baht, and it's listed on a sign at the front desk. I never took 2 or more girls when I stayed, so I don't know if they enforce that policy or not. If you plan on having threesomes, foursomes, or moresomes, you might want to stay at a different hotel, say the Dynasty Grande.
That said, I absolutely loved my stay there, however brief it was. It probably helped that I also really enjoy the Soi 8 area. For whoremongering, you have Lolita's (mentioned above), Aviva Massage, and at least 1 legit place that will give you a HJ along with a professional-quality massage, not to mention limited FL action in some of the bars. Walk around the corner, and you have Lollipop1 and some good Korean restaurants. At the very least, you can't go wrong staying there.