I too started looking for a fixed top stove, however I've found the little butane stove + counter space is really a great option...
You can cook outside regardless, even with a built-in you can store a butane portable in the side door pantry or elsewhere.
Another nice thing about the portable is that you can move it around inside the van, I cook on the pantry from the passenger seat when the top is down, or I want to sit, and move the portable stove to the counter when the top is up and I want to stand and cook. I also cook outside whenever camped, inside only when raining or at a quick stop for lunch or whatnot.
I'm getting a second butane stove to do the 2 burner thing, which is probably the biggest advantage of a built in- you get multiple burners out of the gate. With the dual butanes, I'm not sure there is counterspace to comfortably cook with both (although not an issue with me, 98% of the Sporto meals are currently 1 burner anyway and I'll do the rest outside).
Back to the cooktop, you get single source fuel (well either built in propane or diesel) whereas the butane containers are not sold everywhere... no shortage, just you can't waltz into walmart and pick one up if you're low. Never been a problem for me, but I cook 3 meals a day in the Sporto so it would be rough without stove fuel.
Good luck, and keeping the other half happy... good plan.