Tanks for all the Info, I think I will stick with the 2x12's for the base.
As for the dirt, I don't have any real access to free dirt that I could use for gardening with out just digging it out of a field or something, not to sure about that for several reasons.

What I was planning on was buying several yards, probably around 10 or 15 and using that for the garden mix. I don't remember the exact mixes but they had names like black gold and such. Mostly organics and steer manure if I remember right. I will try to call around and see whats available. And what the mixes are and post it here.

I am not sure about the County Extensions offices, but will try to find something on line.

I have the Square Foot gardening book, some of it I like some not so much. But I was planning on basing my gardens on it.

What I was think of for the glass covers was using the 2x10's cut from full (9 1/2") to nothing over about 4' and then making several "Lids" out of glass and 2x2's so they could be vented and the like in individual sections. I also like the idea that they can be removed as the plants get bigger and then if needed put a plastic "tent" over them using 1/2" pvc or electrical conduit, making a barrel arch for the plants to grow in. At some point most of this would have to come off for the plants like tomato's and peppers as they would get to big. Hopefully!

Thanks again for all the help.

Wolfman