Warning. This is coming from a man. But I lived there for five years and have been to many of the venues involved.

Gossip Grill is your first stop. There used to be a few other Lesbian specific venues (Bombay), but really that's kind of the place in San Diego for the ladies. I've been there a few times with my friends. Its' really a woman's space first. But fun for everyone. Its a good bar. Friday happy hour is usually packed and 90 percent women. And they seem to be taking their partying seriously too.

That being said, San Diego mixes Gay men and Lesbians better than many other places. Historically Mos is another choice (more men than ladies, but usually a noticeable mix - except on Sundays, when its overwhelmingly Gay men + straight women).

Sadly, Bourbon Street is no more, which at times was close to 50/50 Gay men/Lesbians.