Reply by LesB

I have built several similar benches only I use 1 1/8” plywood sub-flooring for the top and then add 3/4” MDF which I seal with varathane so it resists glue and moisture. Also the MDF is easily reversed when it gets dirty and scared up and it is inexpensive to completely replaced.

The one element I see missing in your first drawing it lateral stability. This can be solved either with cross bracing or just adding plywood sheathing to the back and ends. Shelves underneath also makes great storage; which I never seem to have enough of.

-- Les B, Oregon