Cost effectiveness vs structural integrity

I am lost as what my best options are and can't seem to figure out which direction to go.

I want a shop/pole barn 30x40'x 14' H main door.

Like one poster has mentioned in his post, to have a level floor, the rear of the building will have to be built up a good 1.5' to 3'.

Now the 2 options I'm looking at is puring a footer and laying block and with the use of rebar in each cell, filling the blocks solid (probably 3 course up). then back filling with gravel and dirt, rock, whatever and then a nice 6" slab. Building the shop on top of the slab much like you would a house except using anchors plates for the 4x6 posts.

Or option 2 is sink the posts in the ground and using form boarding, filling in between the posts with concrete, of course I would have some type of anchors or rebar into the posts so the concrete would have something to attatch to and then back filling and then puring the floor.

I'm at a loss as to which would be the easiest and most cost effectivness and which would give me the best integrity as well.

Anyone with experience with the two options I have discribed ?

Myself, I'd go with the form boarding instead of the block footing. I don't think I'd attach the concrete to the posts, though, due to frost heave. I don't know what TN frostline is, though, so it may be ok down there (I'm in Michigan).

Thanks for the reply...

Tenn's frostline is only like 4" at best.
The reason I was thinking of attatching the concrete is so it doesn't fall while back filling. Something has to support the wall sections.

If you're concerned about the wall just falling over from its own weight nail a couple of 1x2' to each post to form a keyway of sorts. That would support it IF NO EXTERNAL LATERAL FORCES ARE APPLIED. Would probably also support it from the backfill pushing against it, especially if you alternate inside/ouside backfill. If you're worried about knocking it over with a piece of equipment, a tack strip may or may not stop it and a good wack might even bust out a piece of the rebar or (worse yet) splinter a post while knocking the wall over if it's attached.

Post back with what you end up doing and how it works out.