All of my six band members either do music full time, or have jobs that know the music comes first, so booking is pretty easy as far as availability goes. I always set one full day aside a week (14 hours at least) to do booking and contact info, and accounting info, and promo info, and followup calls, and on, and on, and on...email, fax machines, and the internet have been a godsend, but there is still always more to do.
14 hours of paperwork and phone calls is no where near enough. It just keeps me ahead of current interest. It doesn't give me time to practice, or find new leads. Managers are great, but finding one who will handle celtic/folk/Americana bands is impossible.
The band's been together almost 20 years, and it DOES get tiring....but it beats anything else in town!
I'm normally pro union, but I don't think the musician's union offers much to casual gig bands. We belonged for years, and on at least one occasion they hurt us instead of helping us. I'm sure the union situation can be different in other cities though.
Just my .02