There is a nice weekend of riding at the Mount Dora Bike Fest this weekend. Mount Dora is north of Orlando. The ride is sponsored by the Chamber of Commerce. http://www.mountdora.com/bikefest/index.php

I know that the Seminole Cyclists have a lot of group rides http://www.seminolecyclist.org/
and David's World Cycle has a lot of information for cycling in the Orlando area http://davidsworld.com/

Hope that helps! I'm not in Orlando but live about 1 1/2 hours South in Sebring.