Boy if it was me, I would go with radiant in concrete floor heating. I have done it, and you can walk on it barefoot in the winter. I live in Minnesota, so I know what cold is. But with infloor heating, even a concrete floor is comfortable. You can even use a hot water heater for the heat source (separate from the domestic hot water heater). I installed the same system for another friend in his bathroom, with a zone control, and he has ceramic tile on the floor. Its the warmest room in the house. The whole system is fairly inexpensive. Check with Wirsbo for systems.