I'm determining what towns to stay in of the following:

Santa Barbara
Santa Monica
Santa Cruz
Monterey

a major consideration is the place to stay. Of the above, where would you stay and what hotel/b&b/other? This is also a part of our 10 day California trip. We're definitely going to stay at the Madonna Inn near Hearst Castle one night!

is Big Sur or Carmel another option I should consider?

I'd say don't miss Santa Barbara, and I'd pick Carmel over Monterrey...
Santa Cruz is fine, but don't think it's a must visit, and Santa Monica is a nice place to go...

A lot depends on the make up of your group and what your interests are.

Santa Cruz is a fun beach town with the Boardwalk and a funky downtown. It is also close to some great redwood forests.

Monterey is less "beachy" and more "coastal" - meaning that the coast is rockier and the sand beaches smaller and farther apart. When looking at Monterey, you can consider it with Pacific Grove and Carmel since they are all close together. Carmel is more upscale and romantic. Pacific Grove has great old homes, a nice main street, and a really terrific pathway along the water. Also some nice tidepools. Monterey is larger, not as quaint as the other two, but has more lodging choices.

Big Sur is gorgeous. It is also quite remote and things are spread out. There are a few restaurants, some lodges and hotels, cabins, and so on dotted along Hwy 1 through Big Sur.

just my dh and I are going - it's a "romantic" and exploring kind of trip - we're going in November to celebrate our 8th wedding anniversary. We're going to be in California approximately 11/16 to 11/28