There are a lot of lesbian-run restaurants in Bangkok. While the clientele is usually mixed, some tend to become lesbian hang-out places, especially at night.
674 Soi 101, Lad Prao Road. 081-734-2759
A restaurant/fun hangout place which caters to older toms & dees. They also have really yummy Chinese/Thai food. The owner is super nice, and everyone is friendly. Worth the hike up there! (Near the old Don Muang Airport).
Soi Pipat 2 (off Soi Convent)
A friendly gay boy restaurant with art and yummy food. The drinks are tasty altho, sadly, they only fill the martini glass 3/4 of the way like elsewhere in Thailand.
Soi Aree (Paholyothin Soi 7)
Lesbian owned restaurant and bar on soi aree.
At the Time
81 Soi Aree (Paholyothin Soi 7), 617-1133.
Apparently a 'friendly' restaurant. Please let me know if it's still there.