Typically, ST is an hour or two, but sometimes longer. I think it depends on how well you and the girl get along. I have had STs that started at 9:00 PM and went til 4:00 AM, when I was seeing the girl fairly regularly, and we hit it off real well. But if you just wanted a quickie, it could be bang, bang and out the door in 15 minutes. Unlike almost every ****** I have ever been with in the US, none of the girls I took ST in LOS were intent on rushing. When we get back to the room, then have a drink or two, chat, maybe watch TV a little bit, and get to know each other a little, then get a little bit romantic as a transition to the sex stuff. Of course, there is always the shower before having sex, also, and that takes some time, too,. Usually, they don't like to have sex for more than 15 or 30 minutes, although I have met a few exceptions to that.
If you want to make more of an evening of it, then simply spend a lot of time with her at the bar drinking, and go to the room later on.
I have never rented a room for ST, so cannot advise on the prices there. In this thread, one guy said 300 Baht for ST room in Pattaya, and got a response that it was more for a room in Patong. Most Patong bars do not have ST rooms, as they are not supposed to do that. I was with a friend once, however, when he did ST in a room upstairs from a bar in Patong, and he paid 500 for the room, IIRC.