No real dog in this fight since we use no Propane whatsoever, but here in the city on our November NG bill we used 100 therms which with all the extra fees, taxes & etc., came to about $1.05 per therm all included. Can't say what they charge up in the country since we have had the NG disconnected for many years (there is a NG line running along the road). Our house in the city is almost all gas for cooking, water heater, clothes dryer & heat. Electric bill is minimal except during the hot, muggy summer when we run the AC.
In planning to build a new house out of our barn frame we are considering going geothermal (possibly a horizontal ground loop system), with NG as a backup, but are still considering what will be best. Having 80 acres of mostly woods the temptation to burn wood is high, but I have to consider ease of use for my spouse if something happens to me.
I would put NG with floor heat, you would love it.