Close to the airport (but far enough to not be an airport property) and in a great area for walking is the JW Santa Monica. Renaissance Beverly Hills is nice for walking. Even the Renaissance Hollywood is fine for walking. Hollywood used to be a hole, but it is better now.

If you want to go away from LA a bit, the Marriott in Newport Beach is a great area. You can walk all around Balboa Island and the peninsula. Lots of options, and if you want to do things in LA, do not waste your time at the airport.