I like the way the Rudder Club and the Gulfport Yacht Club do it - a couple of small races a month for club members, and they work around the Regional- and National-level events. This gets you lots of stick time, brings up the level of the whole club, and builds fleet relationships.
As for bigger events, I think two (maybe three) week-long events, and two or three long weekends a year is the most that the average weekend warrior can manage. I'm lucky in that I have a mast-up club in an active region with big events nearby.
$0.02 <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />