Just wanted to give a shout-out to the St. Pete Tennis Center and the leagues they have! I did it for two seasons last year and totally recommend it. Cost is $20/season and you play 1 match/week for ~10 weeks.
You can check it out here: http://www.sptcfirstserve.org
(It's too late now to sign up for the Fall, but I think Winter season starts in January)