Vegan Napa Valley Wine Extravaganza
Welcome to California!
There are two international airports you can fly into. Look at the timing, prices, distances, and anything else you need to know before deciding which one is best. I personally flew into San Fransisco due to more scheduled flights from my location and the vast array of car rental options.
You can also spend time in whichever city you're flying into. If flying through San Fransisco, stop at the Golden Gate Bridge park and/or find a delicious meal before driving off into wine country!
Car Rental
You will definitely want to rent a car while you are going to wine country. Make sure you have a designated driver for the wine part. Uber is available, but it might get costly. At least getting yourself to Napa and Sonoma will be a must with a rental car.
I personally use Travelocity to book my travel cars. They often have free cancellation and no requirement to pay before picking up the car. We ran into a snag with our car rental company line being extremely long due to our delayed flight, but I was able to sign up for their loyalty program and find the special check-in for loyalty members. Cut our wait time down by a few hours at least!