If you're staying in Los Angeles, then I suggest you make Laguna Beach a day trip.
It is a long beach with only a small portion of boardwalk (where you can walk on a boardwalk/sidewalk). Most of Laguna Beach access is via hotels, restaurants, homes.
If you go, be sure to check out The Montage hotel. It's worth going in side simply to get a view from their balcony over their pool. Image (not by me) below.
The road into Laguna Beach can get very, very backed up. It goes through decently tall hills, so you will loose cell phone reception for a few minutes. Just enjoy this as part of the ride.
Parking can be tough (like any beach town), but the best way to find parking is to park away from the beach and walk to it. Walking the downtown part of the city is a lot of fun, it's filled with art galleries, restaurants and more.