When we lived in Europe our bathrooms had heated tile floors.
That really is the ultimate. Cost prohibitive, I suppose, but it was
heaven to get up on a subzero morning and have your bare feet touch
that warm floor.
Of course it was on a timer. No way you'd waste heat on a bathroom
nobody was using at night. But it came on at 0500 in time to be
toasty for morning showers.