Laguna Beach is really cute. Even if it's not beach weather, there are lots of little shops and art galleries just to walk around and see. And, it's going to be in the mid 80's next week, so it might be very nice next month too. : ) The Laguna Playhouse is a good community theater if you want to see a small, local play. From Laguna, you are also close to Newport Beach or you could go a bit farther south to San Juan Capistrano and see the Mission and historic district there.
Santa Barbara is about 90 minutes north of LA, so you could head up there as well. They have a Mission that you could tour and, like Laguna, lots of little shops.
Have you been to LA before? There is so much to do right there in the city! Hollywood, Venice Beach, Santa Monica, Beverly Hills. Even downtown LA has been revitalized recently with lots of trendy new shops, restaurants and bars. You could easily fill your time just visiting the different neighborhoods in LA. The Griffith Park observatory is really nice, you could visit museums on Miracle Mile (such as LACMA) and check out the Getty Museum, which has gorgeous views and is free (just pay for parking). Go see a Movie at the Fox theater in Westwood - it's huge and they do tons of premieres there.
If you want really good food, Mario Batali has a restaurant and pizzeria (side by side) in LA. Reservations should be made ASAP (if it's not already too late). The fancy restaurant is Osteria Mozza and the pizzeria is Pizzeria Mozza. So tasty! There are so many other great restaurants in LA. You're going to have a great trip no matter what you do.