Steve,
Depending on what kind of traveling you want to do, a B can be a great way to go. The Sprinter is a bigger van than the Promaster (Travato). If you plan to go to places where you want to park in a normal car parking spot, then the smaller van would be easier to deal with.
Minimalism is the key to being happy with a van. You really have to consider what you carry and where it goes. There are lots of options out there for compact items. Winnebago is coming out with a new floor plan - the 59K. It may be something to your liking, as it has 2 full time twin beds and lots of storage, and a sizeable bathroom.
Of course, the Promaster based vans are ALOT cheaper than anything on a Sprinter chassis. So consider carefully the kind of traveling you want to do, as well as the kind of money you are comfortable spending and start looking at vans.