Pick two or three:

Disneyland: The Happiest Place on Earth. Half a billion visitors can’t be wrong. (Sometimes it seems all at once). OK, that’s expensive. But fun.

Universal Studios: A theme park that grew out of a studio tour. Check out eBay. You can find some discounted tickets there. And Universal City Walk is a fun place to hang out in the evening after your day inside the park.

Hollywood: Hollywood Boulevard is ready for its close-up, thanks to years of urban renewal and renovation. Enjoy the Walk of Fame, Entertainment Museum, Mann’s Theatre and more. You can see a lot for free. I have also added the Hollywood & Highland complex to my top ten list… it has lots of shops and restaurants, and the Kodak Theater (home of the Academy Awards). I like the El Capitan theater, because it has been restored to its former glory, unlike the Chinese, which was essentially gutted and turned into a multiplex.

Rodeo Drive, 90210: Packed with exclusive shops, full of gawkers. They all came to enjoy the excess. Free, unless you intend to buy something.

Venice Beach: Los Angeles kitsch and over-the-top culture at its best.
Here you’ll find Muscle Beach, street performers and tacky shops galore.
Fun, VERY interesting, but I avoid it after dark, when it gets a little TOO interesting for my taste. And it’s a short bike ride from:

Santa Monica Beach and Pier: Great beach scene and a classic seaside amusement park, complete with antique carousel that has been in a lot of TV and movies. (The Sting and "Three’s Company" come immediately to mind).
After visiting the pier, you can ride a bike south a couple miles to Venice Beach.

Santa Monica Third Street Promenade – Downtown Santa Monica’s shopping promenade is often the scene of movie star-sightings. Just a short walk from the Santa Monica Pier.

Sunset Boulevard: Perhaps one of the world’s most famous streets, it began as a route between the stars’ posh neighborhoods and the Hollywood studios. It runs from downtown to the ocean, passing through the "Sunset Strip" on its way. It makes for a fun drive. Along the way, you see a lot of different neighborhoods. Hollywood, West Hollywood, Bel Air, and Pacific Palisades. When you get to the ocean, stop at Gladstone’s for Fish.

Queen Mary: Once the largest ship afloat, she’s been docked in Long Beach for longer than she sailed, and her elegance never fails to impress. Free to visit. You can actually stay on board, for a price.

Farmers Market and The Grove – A new shopping complex right next to a Los Angeles landmark, The Grove and Farmers Market coexist. Enjoy a movie or shopping, then take the trolley to the Farmers Market for lunch or dinner.
Farmer’s Market is right next to CBS, so walk across the lot to see if they are taping "The Price is Right". You might even get in.

Griffith Park – Home of the Los Angeles Zoo, Griffith Park Observatory, Travel Town, the Greek Theatre, and Gene Autry Museum of Western Heritage.

Getty Museum – The Getty’s architecture is so beautiful that it keeps me fascinated. No matter whether you like their art or architecture better (or maybe you’ll just enjoy the view), the Getty is sure to please. Free.

Attend a TV taping – You can get free tickets at audiencesunlimited.com, or see the booth at Universal City walk. It’s very interesting to see a show being taped. The most popular, by far, is the tonight show. Check the NBC web site for all the details there.

Places to eat:
In-N-Out Burger: Multiple locations, best burger in LA, ask anyone.
Pink’s Hot Dogs: 709 N. La Brea, just north of Melrose. Might see a celebrity.
Tommy’s Chili Burgers: Look for the shack, an LA tradition. Original location at Beverly & Rampart, a couple miles west of downtown.
Canter’s Deli: 419 N. Fairfax, between Beverly & Melrose. Near CBS, might spot a celebrity.
Phillippe’s: 1001 N. Alameda. Great roast beef sandwiches. Near Union Station, Olvera Street. Watch the mustard, it’s hot.

Places to Stay:
In Hollywood, I recommend the Hollywood Celebrity Hotel and the Farmer’s Daughter Hotel.
In Anaheim, I recommend the HoJo Anaheim, and the Candy Cane Inn. If you want to splurge and make this a most memorable trip, stay at Disney’s Grand Californian. You get the full Disney experience.
In Santa Monica, the Holiday Inn Santa Monica is close to the pier and reasonably priced.

Catalina might be good…

San Diego is one great place to visit. The zoo there is known world wide, as with most of Southern Calif the Mission is nice to visit, Old San Diego has many outstanding Mexican Food restaurants, There is Africa USA, Sea world. the weather is good not too hot nor too cold all year long. That is where I like to visit when I am in Southern Calif

You need to go to the Mission Inn Hotel and Spa. seriously! check it out!