Like a couple of others here I prefer a 4' X 8' piece of sheet rock. Holds the pins quite well and is surprisingly forgiving of those knife cuts you inflict from time to time. My bench is made with a sturdy 2 X 4 frame and 3/4 plywood surface, topped off with the sheet rock. The sheet rock seems to last forever and it can be turned over when you tire of the cuts and gouges.

BTW: A simple addition to your bench that comes in handy, is to attach an electrical strip along the edge just below the surface. These strips are close to 8' long and have receptacles about every foot or so. You always have a plug handy no matter where you are working on the bench.

Regards