It's baseball season in Los Angeles and catching a game at Dodger Stadium, just north of Downtown LA is a fun outing for the whole family. The cheap seats can be had for about the price of a movie in LA (I know movies cost a lot less in some parts of the country). There are special promotional days with free gifts or activities, including Jackie Robinson Day (4/15), Fireworks Fridays (4/26, 5/10, 5/24) and Sports Bag Night (4/27).
If you're at Disneyland or other points in Orange County, you're not far from Angel Stadium, where you can catch a game by the Los Angeles Angels of Anaheim. Angel Stadium also offers tours to the public, but they are not daily, so you have to work around their schedule. More Things to Do in Anaheim.
Photo © 2011 Kayte Deioma, licensed to About.com