I learned to fly at KSBA so I'm biased, but if you're going to Santa Barbara I say there is no better airport than KSBA. I can't say enough good things about the people at Signature. If you're staying for more than a few hours they will arrange for your rental car and generally treat you like you came in a GIV. It is going to be more expensive than landing at one of the alternates already mentioned, but it is infinitely more convenient. Plus, the views of Santa Barbara and UCSB on take off and landing are priceless.
Any of the alternates to the south, such as Santa Paula, Oxnard or Camarillo will make for a long drive to Santa Barbara. The 101, the highway to Santa Barbara, drops to two lanes through the very pricey neighborhood of Montecito. On the weekends this creates a bit of a traffic jam that really slows things down. Santa Ynez, which has been mentioned, is the best bet if you're looking for cost over convenience. It is a nice little airport with basic facilities. If you need a car you'll have to arrange through Hertz or Enterprise to have one dropped off at the airport for you, as there are no FBO facilities on the field. Tie downs for at Santa Ynez ae $5 or $10 per night and gas is $4.69/gallon SS vs. $6.95/gallon FS at Signature. There is a $0.50/gallon discount on the weekends at Signature so that brings down the cost a few bucks, but it's still going to cost a lot more than Santa Ynez. If you decide to go there be aware to be on the lookout for NORDO glider traffic in the pattern, especially on the weekends.
If you're concerned about the costs I recommend you call the good people at Signature and they can give you an idea of what you're stay will cost. In my mind it all comes down to a trade of dollars vs. convenience. I'm based in SoCal at TOA, and I regularly fly up to Santa Barbara and tie my plane down at Signature.