One of the biggest music festivals in California is the Monterey Jazz Festival (2000 Fairground Rd., Monterey, 831/373-3366, www.montereyjazzfestival.org [1]). As the site of the longest-running jazz festival on earth, Monterey [2] attracts the top performers from around the world. Held each September—a month that offers the best chance for beautiful weather on the Monterey Bay—this long weekend of amazing music can leave you happy for the whole year.
The event is held at the Monterey County Fairgrounds, which lets visitors enjoy all the different concerts without having to drive from venue to venue. Nine stages put up acts day and night, making it easy to either find your favorite stage and settle in for a long stay and multiple musicians, or wander the length and breadth of the fairgrounds to sample the acts at each unique venue.
Camping is not permitted at the fairgrounds, but you can camp nearby, or get a room in one of the Monterey lodgings [3] that partner with the festival to provide reasonably priced lodgings for attendees.
Links:
[1] http://www.montereyjazzfestival.org
[2] http://www.moon.com/destinations/california/central-coast/monterey
[3] http://www.moon.com/destinations/california/central-coast/monterey/accommodations