Can you carve out about three hours, a couple nights a week, starting at 5PM PST/8PM EST? If so you should join Anonymous! We're a raid guild, so that is our primary focus, and we have a few fixed raid nights per week, plus a few "we'll probably do something TBD" nights ... but we do join each other for groups and such during no-raid times also.
Crucially though we're a
casual raid guild, so you're never obligated to show up for raids, and again we tend to have fixed raid times that you can plan around. While we do sometimes raid at other times, it's completely optional.
If that doesn't sound like what you're looking for, check out the guilds page in the wikI:
http://wiki.project1999.com/Guilds:Guild_List. It has summaries of (just about) every guild on the server, and once you find guilds that sound promising you can follow their forum link or guild website link to learn more about them.
Hope that helps.