Jed that is definitely a heavy duty work bench.
Based on my back, I would say consider making it a bit taller than just waist-high. I so very little standing anymore, and that not for long at all, and the comfortable height for me would be more than just waist-high if I was standing.@MT Stringer - Good looking benches! I think the next one I make will be about that height. I think moving up to waist-high would save me some back fatigue.
I just couldn't resist your lead.A woodworker could use two or more benches, at different hts. Assembling cabinets calls for a lower worktop in order to get at the inside if you have the carcass lying on its back or front.
Mine is 8' x 4' and is also my outfeed table for the contractor table-saw, so that determined the ht. NOT comfortable for cabinet assembly!