Since you are staying for 7-10 days and it's your first trip plus you say you're not that into the sightseeing this time I'd give Bangkok a miss this trip and go straight to
If you're looking for the very pretty ones and you're limited on time your best bet would be to hit the Go-Go's, people with current knowlege on the top ones can weigh in there although Happy A-Go-Go and the Superbaby/Supergirl ones are usually always strong. I second the Residence Garden choice, a nice suite hotel not that far from the action, absolutely no problem bringing guests back to the room, even a less obtrusive entrance from the parking stairs to the elevator if you're shy and back before they lock the gate at around 10 P.M. But no one gives a second glance at reception, they've seen it all over the years. Depending on the time of the year their rates range from 1600-2500 but if you mention that you're a member of the FLB message board when you book via email the rate is 1399 per night. Here's a link to the hotel's Web site:
http://www.theresidencegarden.com/