Heat Pumps and Electric Heating - Seems to run too long...

Our heat pump seems to run ALL DAY. We have two separate thermostats (one upstairs, one downstairs), set at the same temperature. Clearly, hot air rises, so the heat very rarely comes on upstairs. However, it seems to run almost all day downstairs, when outside temperatures are above 40 degrees. If the thermostat is set at 65 degrees, I will check it and it will say "64.5" degrees. Since the house is not at its desired temperature, the heat pump keeps running. Is this normal? Our house is only two years old -- we have lived here for less than a year and have, therefore, not experienced a winter here yet. Our house is very open and we have 12 foot ceilings -- is it possible all of the warm air is escaping upstairs?

Additionally, we have several rooms we don't use and we currently keep these doors and vents closed -- is this a good idea?

Are your air filters clean????? 40o outside is the freon charge right???? Is the big copper line warm to hot at the inside coil when running. The pump should bring the temp up to what you have it set for
Our house is very open and we have 12 foot ceilings -- is it possible all of the warm air is escaping upstairs?
Yes the warm air will go up there.

Additionally, we have several rooms we don't use and we currently keep these doors and vents closed -- is this a good idea?
Most of the time it dont pay to close a room off in the home. To close a register some is ok but Id say not all the way. The walls inside the home dont have insulation in them. So to close off the heat in them just makes their walls cold to the other rooms
I think you have found by now. In winter the downstairs will do most of the work and summer the upstairs will do most of the work. ;)