For me it would depend upon where the members of the group are from and the ages and genders, oh, and how much you might want to spend....
If the beach is close by to most of you, I probably wouldn't bother with the beach, but if it isn't, orange county beaches are great. I like Huntington Beach by the pier and eating at Ruby's on the pier. They also have bikes that can be rented to ride on the strand.
If you have girls, I think a trip to American Girl is a GREAT experience. Though, make sure you have the same expectations about how much will be spent. Dolls cost $95, their animal friends 20-30. They have a really fun lunch and dinner (I recommend dinner) at the American Girl Cafe. The Grove is a neat mall to go to as well. It's outdoors and has a musical fountain and trolley car. If there's boys in the group who wouldn't want to do American Girl, then there's a movie theatre they could go to, or the La Brea tar pits are close by. When we go to American Girl (or anything else in Hollywood) we always go to Sprinkles cupcakes. They are the bestest. They are located in Beverly Hills, about a 10 minute drive from AG store. If I wanted to make a really full day, I'd go see Graumann's Chinese Theatre, El Capitan, and the Hollywood Walk of Fame and get pictures in front of the Hollywood Sign (which is easy to do from the upper levels of the shopping center at Hollywood and Highland.
If I wanted another theme park, I'd do Sea World.
Often, on "down days" we've done Disney without doing the park....later breakfast seating at one of the character meals outside the park, play in the pool, dinner in downtown disney, build a bear, maybe a movie at the theatres there. Get DD a makeover at what used to be club libby lu, I think it's Club 365 now. The kids, especially when they were younger, complained they didn't get enough pool time, so that would help solve that issue.