I've never been to the Empire, I think they mostly play top 40 dance/r&b during the nights they're open. sounds like a perfect place for a SY show!
I don't know, maybe I'll go if I'm really bored one night, then I can tell you about the acoustics and whatnot. But it doesn't look like a huge place, and you won't have to worry much about parking...it's pretty easy to find a free place to park in sacramento at night. Have you seen any good shows in SB lately?