How much time do you have?
I ask, because while they could be relatively short trips, you could fly the Route 66 route. Since old Route 66 ends in Santa Monica, you could take a day and fly the route: something KCMA - (if you have the money for the landing fee) KBUR (for Pasadena) - KEMT (for East Pasadena/Asuza/Monrovia) - KCCB (Upland) - KSBD - KVCV - KDAG - KEED (Needles) - KIFP or A20 (covers Oatman, AZ) - KIGM.
That would cover airports at or serving every city in California that was/is on Route 66, all the way to Kingman, AZ. With some of them still in that classic 1930s/1940s/1950s style, you’d cover a good amount of history and Americana in such a route. Additionally, if flown right, the most congested airspace you’d enter would be Class C, with Burbank.