Well, its on Suriwongse Road really, right opposite the Siam Heritage and Tarntawan, between the Tawana and the (yet to be opened) Le M├йridien.
De Arni Bangkok is a 'boutique' hotel with 56 rooms finished to a much higher standard than TakeASeat or Baan Saladaeng and may be of interest to those adventurous enough to consider something other than the tired Tarntawan. They have some good 'soft-launch' prices at the moment from about THB 1,400 but rates will probably double when the hotel is fully established.
It's been open for a few months and they have at last launched a web-site: dearnibkk.com/ which doesn't function well yet, but better details pictures and prices are available on Agoda: www.agoda.com/asia/thailand/bangkok/de_arni.html
I am told that De Arni Bangkok is gay friendly, but I can not confirm any joiner policy. However, if you check it out on this site: th.88db.com/th/Services/Post_Detail.page/travel/hotel_accomodation/?PostID=407757&lang=en-us you will see that one of the search engine tags is 'gay hotel bkk' so someone there has decided to target the PLU looking to stay in the Silom/Suriwongse area.