I stayed at the Baan samui.
very nice hotel and restaurant.
But definately not friendly towards any girls you might want to bring to your room. Their security was very good and all entry to the rooms was guard by a security guard. 3 on duty at once.
Will allow girls at a cost of 3000 baht per night.
I have been to Phuket and Pattaya but like the pace of Koh Samui.
And there are more than enough girls .Hell you only need two or three a day if you are a butterfly or less if you are not.
I am going to Koh Samui for three weeks in March and I am staying in Lamai at this hotel. beutiful and only 950 baht per night.
http://magnusj.org/wanta/index.htm
Cheers
have a good time