While at HD recently, I found a large bin full of 4' premium 2x10s in
their culled lumber for $0.51 / piece. I've been meaning to build a
basement workbench, and figured these would be perfect for the work
surface. My plan is to lay them down side by side like a deck and
cover them with a piece of 1/4" oak ply.

My question is, given 4' boards to work with and no floor space
limitations, how deep would you make the bench. At 4' I won't
really be able to reach the peg board in the back, but I would have
that much more surface on which to work.

My other question is, how high would you make it? Is there a rule of
thumb such as x inches above the waist?

Thanks in advance,
-T