The international airport in San Diego has the code SAN.
The best deal and location appears to be the Marriott Vacation Club in downtown San Diego (see the Travel tab). It is very close to the wedding reception venue and a very affordable option compared to the Double Tree and Homewood Suites by Hilton near the Founders Chapel. The only disadvantage is that parking is $45 a day, but combined with current rates for rooms, it is still a better deal than the other two hotels mentioned.