Well for one, just exploring the metro area itself is interesting. So many movie and music related sites (pop culture history) and a ton of cool architecture.
Then you have stuff like the Griffith Observatory, the Santa Monica Pier, Venice Beach and the boardwalk, the Getty Center, the Getty Villa, the Academy Museum, all of the museums around Exposition Park, Hollyhock House, the Original Farmer's Market, La Brea Tar Pits, movie studio tours, Huntington Library/Botanical Gardens, the Peterson Automotive Museum... among other things.
All of that worth seeing at least once IMO (and there are several things on that list I haven't seen yet). I actually think the LA metro (which is actually a ton of different cities) is my favorite metro area to visit in the US; it's unique in a lot of ways.
Obviously not everyone is going to be interested in all, or even most, of those things -- but my point was simply that the breadth of what is offered in/around LA vastly exceeds what's offered around Orlando outside of theme parks.