We looked at the Pacifica hybrid when we bought ours, but that year (2017) it was brand new and the mechanic recommended against it until Chrysler had a chance to work out the kinks in their hybrid technology.

If I had to get a new van today, I'd consider it (or their all-electric next year).

I have a 2017 gas Pacifica, purchased in 2016, and yeah, I would suggest not getting a first model year vehicle.

The PHEV might be nice, but you lose the underfloor storage and can't fold the middle seats into the floor.

The seats in the PHEV are nicer than the folding seats in the gas model and the pop out pretty easily. We have the passenger one out full time, easier to get to the kids in the back and allows for more storage when travelling.

I'd imagine a EV minivan would use a heat pump instead of a resistive heater. That'd have a much smaller toll on the winter range.

Yeah, if it was a pure EV I suspect that's the route they would have gone. As a plug-in hybrid, it matters a lot less (since you only have ~30 miles of battery range anyway).

Why would a PHEV use a resistive heater instead of running the engine cooling system?

Generally plug-in hybrids run off the battery, like an electric car, until they discharge it and need the engine.