My initial thought is Morro Bay. We spent a week there a couple years ago over spring break and found many nice hikes - Morro Bay State Park, Montana de Oro State Park, the beach itself - plus one day we drove north to Cambria and several things to do up that way. But Morro Bay is 4 hours 6 mins without traffic according to Google plus no Marriott - so perhaps not Morro Bay proper.

The Vespera Resort in Pismo Beach would put you close enough for most of the hiking we did and a little closer to San Juan Capistrano.