Gardens, trails, parks, San Diego Natural History Museum, The San Diego Museum of Art, San Diego Air and Space Museum, Japanese Friendship Garden and Museum.
South of Del Mar, hike in Torrey Pines all the way down to the beach, with great views up and down the coast.
There are multiple bike rentals (including tandems) in PB. The boardwalk runs right along the beach and you can follow side streets all the way to La Jolla to watch the sea lions.
Watch the sea lions and seals in La Jolla.
Beautiful beaches, bike paths, Hotel del Coronado.
Many great breweries, but here are a few options: Pizza Port North Park Pure Project Burgeon Beer Lost Abbey Viewpoint Brewing Co.