What about Santa Monica? I did this trip a few years ago (map on the linked page) and the riding was outstanding.
California Cycling Camps - Santa Monica Mountains - 2015 Bike Camps

If you do stay in the Carlsbad area, there's nice riding around Temecula/Fallbrook too.

Or stay in Encinitas/Solana Beach (cute little downtown) and do the Swami's ride.