Paso Robles sits on US-101 midway between Los Angeles and San Francisco — about 3.5 hours from each by car in normal traffic. This is the most practical way to arrive. The drive south to Morro Bay (30 minutes) and north to Salinas are both scenic.
Amtrak's Coast Starlight stops at the Paso Robles station on Pine Street, with service north to San Francisco and south to Los Angeles. The train is slower than driving but the route along the coast south of Santa Barbara is one of the more beautiful rail journeys in California. The nearest commercial airports are San Luis Obispo Regional Airport (50 km south, served by United, Alaska, and American with connections through hub cities) and Monterey (90 km north). Los Angeles International is feasible for those renting a car.