Some of the earlier responses to your post give very good advice. I completely agree with suggestions that you look at as many different models as possible - RV shows are an excellent place to see a lot of different vehicles. Renting before buying is also a very good idea.
Your post indicates that you value efficiency and economy and I believe that you are correct to target Class B's. For your situation I would also suggest looking at Sportsmobile (www.sportsmobile.com). They allow you to custom design your class B van to fit your needs. B's have a limited size and it it important to make that size work efficiently for your needs.
Other points:
Class B vans get 14-20 mpg depending on make. Class C's get 8-10 mpg. All the class C's that I have seen seem to be designed to maximize the number of people that can sleep in the RV. For you, this would largely be a waste of space.
Since you are a photographer in the West, I am sort of guessing that you might want to go into some desolate areas. If this is correct, you might want to look at the very off-road capable B's made by Sportsmobile or the fairly small class C's made by Tiger Provan based on pickup trucks which can be 4 wheel drive. Both are fairly pricey.
Advanced RV Sprinter