I have heard pros and cons regarding insulating the floor with fiberglass insulation in a conventional foundation. Any suggestions? I also heard that instead of insulating the floor, I should spray insulation on the block wall instead. Anyone know?? We are building now so need an answer asap. Thanks!

You should check you insulation codes. Several years ago, the codes said to insulate all foundation walls, then they changed to insulate the floors. I always insulate between the floor joists with rolled insulation, paper on one side.

Why not use 2x3s or 2x4s as floor joists and use 1 7/8" or 2" rigid foam between? This will give you between 10 and 14 R on the basement floor.