The crowd at Underground 39 is as Icon describes it. I've been there 6-7 times, and only once was there another farang there. I like the layout, it gets very intimate because it's small, and the fourth floor is nice with a small, semi-open room on a little mezzanine. I like the layout at the Door better though, particularly the open-air top floor with a steam room and a dry sauna. But it's more of a trek to get out to the Door; 39 is more convenient because it's so close to the Saphan Kwai sky train station. Still, Farose, in spite of its wornout facilities, outshadows the others in terms of number and action and sheer sexual atmosphere. As for all these and other local saunas, the majority of the customers are mainly interested in other asians. But I've never been to any of them and not found someone who is also interested in someone like me. I went to Sauna Mania for the first time yesterday, on their "extra" naked zone night, and I was very impressed. The place is very clean, the maze on the third floor very conducive to action, and the crowd was fun.
S Casa (sorry I misspelled it the first time) is located on Soi Glang Mueang, sidesoi 6 on Lad Prao, just next to the intersection with Rachadapisek. It's one of the few local saunas that I have not been to yet, simply because my thai friends have told me that they have few customers. That may change, though, as the owners seem to be beefing up their publicity with promotions and party nights. The facilities are supposed to be very, very nice.
Thai-reading people will find information on all the local saunas through their ads on the local gay web sites, such as
www.69clubx.com www.thaiboyx.com www.gboyx.com www.miragemx.com www.thaimeeting.com www.thailandout.com www.palm-plaza.com
For me the local saunas are a nice break from Babylon - a change of atmosphere and a change of crowd. But in terms of opportunities for a farang, none of them can beat Babylon. It's simply impossible, even if you look like a troll, not to score at Babylon.