I hesitated about staining the shelves. Somebody pointed out, "it's in a closet, go for it".
I chose a dark red (Minwax Red Oak 215).
I worried about the stain on the edges of the plywood.
There were a few spots where the dado cuts chipped the plywood, so I looked into wood filler.
I tried the Minwax Stainable Wood Filler. It looks/feels like beach sand. Odd.
Seemed to blend okay.
Test everything on scrap first!
The stain was much darker than I expected (brown, not red)
It did not look good on the edges of the plywood.
But it looked worse on the edges with the wood filler. (I think)
Well, I used the wood filler on the deep gouges, but not on the edges.
I sanded everything with 220 grit sandpaper and an orbital sander. Fairly quick job.
I applied 2 coats of 215 (2x 8oz cans, no left overs). 6 hours after each coat.
FYI the stainable wood filler doesn't stain. (the yellow stripe just above the shelves)
Applied a coat of Minwax Fast Drying Polyurethane (32 oz can, used less than a 1/4) to all of the stained surfaces.
After 6 hours, I felt the surface. Very rough.
So I lightly sanded (220 grit) the top of the shelves.
Applied another coat (again just to the top of the shelves)
24 hour cure. Very nice!
Most important thing I learned: I need more light.
I found a few spots where I missed stain or clear coat.
Next I need to figure out how to mount it.
One last thing. Remember to clean the stickers off with rubbing alcohol first.