I have a 2 story house with one thermostat upstairs, all of the intakes on the ceiling(s) upstairs, a slab foundation, and the registers that heat comes out of are all in the ceilings. This adds up to a freezing cold downstairs (where we spend most of our time) in the winter, and a toasty warm upstairs. I'm no expert, but I can't help but think that a ceiling fan in the stairwell (to push hot air down), and to somehow move a couple of intakes to the lowest points on a couple of the walls down stairs would actually allow the air in the house to circulate, and heat the lower level. It feels like there's a 20 degree difference between the two floors. Anyone have any ideas of how effective my idea(s) would be, and how much of a pain it'd be to put ducts in the walls somehow to pull cold air off the floor on the lower level? Thanks!

Close off all the supply vents upstairs and let the heat from the lower level heat rise to the upper level. A ceiling fan would help, if for no other reason, it would create some air movement.