The LAX area is not really a recommended destination for your last couple days. It has a big lineup of hotels along the airport access road area (Century Blvd), but those rooms are usually filled with airline crews, bumped passengers, and early departure types. Though the western reaches of LAX are very near the coast, a beach is definitely not walkable from those hotels, but one can Uber/Lyft to one.
Santa Monica is a great beach spot with a nearby popular walkable "downtown". I believe a new subway/train now goes to Santa Monica from points inland, but Angelenos can advise on that. That train goes nowhere near LAX, however.
You'll have to get a taxi/shuttle to the airport, but worth it to avoid the LAX area.
Local Angelenos can also advise on the El Segundo/Manhattan/Redondo/Hermosa Beach area beachside hotel options you may've missed.