The first trip The Fireman and I took as bonfide empty-nesters was to Catalina. Sadly I had never been there. The Fireman had many many years ago. Catalina is an island right off the coast of Southern California. But don't let that fool you, you completely feel like you're getting very far away. Since returning I've been spreading the love of Catalina. The island was clean and charming and even though it's a tourist trap you don't feel completely sucked in.
The Ferry! I recommend you go early, make reservations and upgrade to an inside seat. The plus is you can get your Bloody Mary on during the hour ride. And since you won't be driving on the island you might as well live it up.