I've owned a Vanguard Nomad for about a year now and sail it every weekend down here in St Pete, Florida. She's exceptionally stable, very comfortable, easy to rig but she still provides plenty of excitement when pushed -- especially flying the spin. Downsides? She ain't cheap and she doesn't point as well as a Capri 16.5 or a Precision 18.5 - but once she's on a close reach; watch out!!
This boat was DESIGNED for exactly your purposes - a fun, stable and safe family daysailer. Here's a link to the designer's Web page:
http://www.bana.com/nomad/
Have fun and good luck in your search!
Jon