I'd paint the framing a color that shows you've got a bench sitting there, not the same as the lower walls.
I'd also double up the the top with another sheet of plywood, One sheet of 3/4 is mighty flimsey even with your reinforcement stud on 24" centers. My bench is triple 3/4 Ply. Also put a front finished edge on it so you don't get splinters from it (you'll be surprised how cut edge plywood splinters) and for a top surface, I'm partial to a formica top. They are cheap, easy to install and you don't end up with a greasy stained bench top. A wooden top with oil becomes sticky and attracks dirt like a magnet. Once the dirt settles it can at times be hard to wipe away.
Any spills on formica wipe right up plus I have a white top and use a black sharpie on mine, as you would a white board, to make notes that I may need. If the notes are to be kept I'll transfer them to my notepad on my iPhone or write them on paper. If they are temporary measurements or notes for the current project, a quick shot with carb cleaner, a wipe with a paper towel and presto! They are gone and you've got a nice clean benchtop.
Yes, it scratches, yes it can chip but so will any other material except metal. I don't like metal for it is prone to dent's and scratches, not to mention a tad expensive. Metal is also literally COLD to the touch even in the summer.
When the formica is shot (and it will takes literal years for this to happen), simply sand the existing formica surface, apply glue and viola'!!! a brand new bench top!
BTW I'd do a white bench top for the light reflective qualities of it. Also I prefer a glossy surface, not the matte surface. Stains and marker wipe off so much easier from a glossy finish.
Dave