There are radiant heating pads now that eliminate the chill you get from the concrete slab. That would really be the way to go in a home like that. Radiant heat paired with solar.
That's tough when you don't have room to gather. We've never lived in a home we could entertain in until now. Even our bungalow was sectioned off into small rooms. A garage is a good alternative! You can do a lot with that space.
That is a good point. I always seem to forget about the radiant heat they have now. Like I said, we don't entertain a lot, but part of that is because we just don't have the space for it. On the deck we do, but the weather doesn't always allow that.