I'm remodeling the place and my contractor has suggested lowering the
10 foot ceilings to install central heat. I don't want to do that, but
I'm at a loss for alternatives. I'd like to install radiant floor heat
on the first floor, and gas fireplaces or heaters on the other floors.
I really like my old space heaters, but my sister doesn't, and we
should probably replace them anyway. I have a newer space heater that
doesn't work as well, plus it's downright ugly. Direct vent gas
firelplaces are being considered, but that requires punching a hole in
the wall, which I'm not too keen on.

I really don't like electric heat (unless it's forced air) because
there's no air circulation ... rooms get smelly, too humid, you name
it, without some sort of really good air exchange system ... which does
not sound reasonable for you ... or, you might as well put in central
heat/cooling. I do like easy zone control ... I have 2 forced air gas
furnaces ... one for each side of the house ... it's an older home with
a "granny flat" built on. We live in the "granny flat", I have boarders
in the other part of the house. And what would be ideal would be to
further zone that other part of the house into upstairs/downstairs
zones ... the upstairs gets hot in the summer so needs ac, the
downstairs does not, so does not need ac.

The (zone) arrangement you have sounds ideal to me ... just needs some
refurbishing. Sure, direct vent gas fireplaces require a hole in the
wall, but imo it would be well worth it ... especially since you've
already got the gas lines installed.

If it was me, I'd stick with the gas ...