There are tonnes of restaurants in Los Angeles, and many of the best need to be booked well in advance, although step down a tier or two and they can almost always get you in. Expect the waiter to turn up a few years later in a movie, as almost everyone working menial jobs in the city seems to have that dream.
A good bet for an excellent meal, and the chance to see a couple of celebrities while you eat are the restaurants at the Universal Studios, while for evenings out, head for the Italian restaurant Ago on Melrose Avenue in West Hollywood, which is highly recommended, or an excellent choice for families would be the Crocodile Café, which serves traditional American food at several branches throughout the city.