I live in the cold north. I was wondering what you would use as a subfloor in a split level house. I was planing on a sandwich of
vapor barrier/2x2/insulation/vapor barrier and 1/2 floor sheathing. Does this sound good? Please let me know.

NEF, I don't think you want that second layer of vapor barrier. Is your floor damp? If not, just put down pressure treated 2x4s and use a good foam insulation between them. Then cover with 3/4 plywood. The vapor barrier is to protect the insulation. A good foam is not affected by condensation.

Another thought - I haven't researched this but have you looked into a heated floor? I've seen shows where hot water is run through pipes in the floor to provide warmth.

If you are interested in heated floors, look at the site: Warmfloorcenter.com for information. Rodney sells and installs radiant flooring systems. His number is 1-800-562-8036 if you much rather talk to him directly.