Yesterday, one of our boys came over and helped me construct my dream workbench. The thing is built like a battleship. The legs are twinned 2x4s which are stronger and more stable than 4x4s. The frame is lag-bolted to the wall studs and the top is a pair of 3/4" plywood sheets. I weigh about 200# and I can lay on top of the thing and move around all I want and the workbench doesn't budge. Once I get the power bar installed across the top and put on a couple more coats of Helmsman Spar Urethane, we'll be ready to rock.
Battleship photo included for reference.