Starting from scratch! Which model of van do you recommend?

To the op. If you plan on doing any mods, or replacing the front seats, make sure to talk to your insurance agent first. I'm pretty sure all the new vans (Chevys included) have airbags built into the seats, and are part of an integrated safety system. I know Roadtrek can't even recover them because this.
I would also talk to the car dealer about the warranty being affected.