Square foot gardening is a great idea. It takes more of a start up cost up front, and the mix can be expensive if you decide to do it just as it's described, but overall the concept of 4'x8' raised plots densely planted works well. Some crops, like squash, need more sprawling space and do well in the old fashioned mounds.
This past winter we used IBC totes cut in half to plant in our greenhouse. They are available on Craigslist for cheap, and their (almost) 4'x4' size make them really manageable.
The spinach did well. We were planning on putting in an aquaponics system, but the cost became too much for our budget. I have a friend whose 8'x12' greenhouse produces year round in Reno. If you are going to do a square foot or a greenhouse I'd recommend that you start off small and manageable before putting too much money into a large production.
~Good luck!