Catalina Island (not done it myself, maybe next time)
I did it from Van Nuys via the LAX overhead. I didn't see the sea for the whole trip, due to the marine layer fog, but the airfield (Avalon - the Airport in the Sky) is at 1600' on a hill and was sticking up above the fog. A small landing fee (the first one I have ever paid in North America) and a great restaurant for lunch (Buffalo burgers). Then back via the same route, with a detour to Burbank for an ILS.
A great trip. The only note of caution is that the runway is quite rough. I went there with an instructor and he did the landing, but let me do the takeoff.