Venice Beach is a great place to get a suntan, not mention a henna tattoo, get a workout, go shopping and generally watch the freaks go by. The boardwalk stretches all the way along to Santa Monica and is for the most part edged by alternative shops, tattoo parlours, artists and street performers. It's fun to just wander along and check out the sights - mostly human. And you can hire rollerblades, bikes or surfboards at either end if you fancy being a bit more active.
The beach itself is great, miles of golden sand and crashing waves. Don't necessarily expect to be left in peace though. When I was there, we were entertained by this big black guy balancing little rocks on big rocks. He took exception to people watching him though and demanded money. He was even more insulting to a random tv crew that happened to be there - this is LA after all.
People watching is the best sport at Venice Beach - it's a genuinely alternative area, with its share of old hippies and free thinkers rejecting the usual LA ideology. Look out for the poster man who's clearly aching for an argument, a few examples of his posters read 'Jesus was Gay' and 'Hitler
was right.' Most of the shops are of the alternative kind - candles, ethnic knick knacks. There are a few cheap clothes shops and it's a good place to get cheap sunglasses.
Another great spot for people or rather body watching is Muscle Beach. Here you can watch guys pumping iron in the midday sun, mad but impressive. There's also a basketball court if you fancy a game.
Venice Beach is a definite experience and you don't need to take a book along to be entertained. One thing though, it is a safe area - during the day, but if you're a lone female, be prepared for all the comments especially down Muscle Beach end.