In my particular case, a poured concrete foundation was out of the question. It was too expensive to haul concrete to my home, and it was not a job that I could tackle myself anyway. Be sure to give proper consideration to pouring a foundation, it might make sense for you even though it didn't for me.
The foundation design I went with was to use concrete block basically as the form, and then fill all of the the ports with concrete. The original plan was to buy bags of concrete and fill the ports with that. I later found that this posed two problems. First, that is far too much concrete to be moving around by hand. Second, that method would create cold joints because it would be impossible to pour the entire thing at once. A better solution was to have a concrete truck come up and fill all the ports. One load of concrete would be plenty so the cost was not terribly bad.
The concrete also needed to have rebar installed for additional strength. Some of the blocks needed to have holes drilled in them to hold the rebar.
But before I could do any of that, I needed to have a 32'x24' trench dug out to place the blocks in. Well, this process took about 2 months due to the huge amount of rock present in my yard.
I knew I needed something that was capable of digging large amounts of soil and rock quickly. I went to a heavy equipment auction in a nearby city and found a good deal on a mini-excavator (also known as a track hoe). Basically it runs on tracks, has a backhoe for digging and a push blade for filling in and smoothing out everything. It wasn't in very good condition, but it served my needs perfectly well. At the end of construction, I sold it for nearly what I paid for it. I wish all of my choices worked out this well.