I've also been considering which party I will hit:
Something mainstream like:
Halloween Villain Reunion Party at Route 66 RCA (probably not go there, as I would assume it will be the most jam packed, I mean, impossible to move!)
The Halloween Asylum at Koi Lounge Bar (sponsored by Jagermeister!)
Haunted Hospital at The Mansion RCA
Trick or Treat Halloween Party at Fallabella in Siam
or something more naughty like
The Pimp Halloween party, various Nana Plaza bars having things, Cowboy, etc will all have Halloween theme outfits for girls and decorations for sure. I wonder how well Saphan Kwai girly bars will be in holiday spirit, anyone been there in previous years?