Things To Do
Balboa Park
Sprawling park in the middle of the city. Plenty of picturesque sites along the El Prado going from the San Diego Natural History Museum to Nate's Point Dog Park. Has 17 museums (everything from art to science to model trains). I suggest parking near the Natural History Museum museum lot along Park Blvd. You may also use the Zoo parking lot without paying for the zoo on really busy days. About a 2 mile drive (10 mins) from the wedding venue.
San Diego Zoo
One of the best Zoos in the world. Go early if you want to see the animals actually move around. The zoo is technically within Balboa Park.
Coronado Beach
If I had to pick one beach in town to visit, this is it. The island of Coronado is a ritzy little beach town, so its a good place to walk around after you relax on the beach. The island is where the Truman Show was filmed, if you want to get a sense of the vibe you are walking into. 13-14 minute drive from the wedding venue (6-7 miles).
La Jolla Cove
Amazing coastline views. Leave the seals alone. La Jolla is considered the fanciest part of San Diego so go ahead and explore the town while you are here. 13 miles from the wedding venue (20 minute drive if you can avoid rush hour).
Tacos El Gordo
Go here for meat based (particularly adobada) tacos. Don't be scared you are not quite in Mexico yet. 15 minute drive (10 miles) from the wedding venue.
San Diego Neighborhood Guide
See this link for a general overview of neighborhoods around the city.