Re: leather seats: hot in summer, right?
I have a nubuck leather La-Z-Boy recliner at home. It's the softest leather I've ever sat in. There is no heavy finish to interfere with breathability, so it is comfy whether I'm hot & sweaty or I'm cold. Too bad the car companies can't put that really good-quality leather on their seats.
To me, most of the leather they use in automobiles feels not much better than vinyl. It certainly doesn't breathe any better than vinyl (without vent perforations, I mean).