The most popular day trip is into the Santa Ynez Valley wine country over the San Marcos Pass — Highway 154 climbs through chaparral and oak savanna with viewpoints over the Pacific behind you. Stop at Cold Spring Tavern on the way over for lunch. The valley contains Solvang, a slightly kitschy but real Danish-themed town founded by immigrant farmers in 1911, and Santa Ynez with its 100-plus wineries that featured in the film Sideways.
The Channel Islands National Park — particularly Santa Cruz Island, the closest — is the other major excursion: take Island Packers' boat from Ventura (45 minutes south) for a day or overnight on truly wild country. Bring everything you need; there are no shops on the island.
Further afield, Hearst Castle at San Simeon is a 2.5-hour drive north — William Randolph Hearst's improbable hilltop fantasy of a Mediterranean palace. Los Angeles is 90 minutes south on a clear weekday morning, longer most other times.