I'd suggest Santa Barbara, a nice town just 150km up the coast from LA. During the three-hour drive up there, you can gaze at the coast on your left and farmland below the mountains on your right. LA will seem so far away.
A really nice place to stay is Fess Parker's Doubletree Resort, right across the street from the beach.
If you don't feel like driving a rental car on the other side of the road, you can take a train from Downtown LA's Union Station. Union Station isn't very accessible from LA Airport so you can take a taxi or ride three urban rail lines.
Santa Barbara Station is a few blocks from the beach. More city info is at
www.santabarbaraca.com .