San Luis Obispo is between San Francisco and Los Angeles on the coast of California. Flying into SFO and LAX are viable options, but it means dealing with the infamous California city traffic. SLO has its own small airport with direct flights from Denver and Phoenix. It is slightly more expensive than the larger airports, but saving on gas and driving time often makes it the best choice.
The wedding venue is in Santa Margarita, which is a small town 20 minutes north of San Luis Obispo. SLO has many hotels and Air BnBs options, and the beach is just 15 minutes south if you want to see the ocean while visiting. Using this link should get you 10% off your stay at the Hampton Inn in SLO.
If you want to see vineyards rather than the ocean, you could also stay in wine country. Atascadero and Paso Roles are cities north of the wedding venue, 10 minutes and 20 minutes away, respectively. Both these cities also have hotels and Air BnBs.