I'm a tick under 6 foot in my work boots. The shortest guy in our shop is 5'7", and the tallest (that does any fab work) is 6'2". Neither one has any issues with table height.
Of the 3 we currently have in the shop two are 5'x10' 1.25" plate steel. the framework is 6" wideflange, with sched 80 6" pipe for legs. The third one is a bit lighter, it's only 4'x8' and 1" plate.
My last job I built a fab table where the table top unbolted from the framework beneath it. It was 1.5" plate, 5'x10' and after I got everything welded up we chucked it on our Kao ming CNC mill and machined it dead flat. The legs had adjusters on em and we used our transit to level it to within .020". It was an easy 4000 lbs with legs, and a pleasure to work on...although it 'career death' to weld anything to the machined table top. lol.
Rene