whatever you end up with, chances are, some day you'll wish it was a little larger... :soapbox:
since the main reason to get a thick slab is so it won't warp from the heat, as long as you don't don't use the table top as a reference for how square everything is, you can go a lot thinner and save some $$. i use a lot of clamps and welding squares and don't need to worry about the top not being true. save some $$ on steel and spend it on some FireBall Tools. they're a lot easier to move around and store
