stained concrete: very cool look, Le Corbusier would be happy.
radiant heat:
We have it in the studio.
It was fairly cheap because we put it in ourselves. I didn't want to waste all the work we spent isolating by having a radiator or baseboard make noises and I didn't want to run the air handler to force hot air. Our rooms are fairly tight so it's very efficient. It works great and is easy on the sinuses.
Every room is on it's own loop with valve so we can direct heat where we need it.
Incidentally I've got 300' of 1/2" pex tubing left over if anyone wants any
cheers,
joel