I live in LA, so thought I'd chime in; I agree with posters here, Santa Monica is much safer than Venice Beach, especially if you plan to walk around and explore a bit at night.

If you pick Santa Monica, you can select your place based on distance from the intersection of 3rd and Broadway, in Santa Monica. 3rd and Broadway is where the 3rd Street Promenade starts on one side, and is always fun to walk around this area. The Santa Monica Pier is also close to 3rd and Broadway.

I don't know how much time you have in LA, but if you visit on or after the 28th of July, you should absolutely not miss going to Huntington Beach. The US Open of Surfing starts on the 28th and goes on for like 7 days or so (usopenofsurfing.com). It is an amazing experience and a lot of fun, and you just have to check it out if you happen to be in the area at that time.

I have visited USA and Canada many times yet never driven except once. It takes a bit of getting used to as you automatically want to turn on to the "Australian side" of the road. I drove from San Francisco to LA once and had to concentrate and keep reminding myself about what side to turn on. Even using the blinker seemed strange as did looking in the rear vision mirror. I would suggest you don't start driving on the first day you get there. You will slowly get used to doing things on the other side of the road, even just looking left first before you cross the road.

I would suggest public transport so you can take in the sights.