I need a durable, clear finish for wood.

Thank you Tim. I plan to do a light sanding to start. As Buffalobo pointed out, I feel like my biggest limitation is the material I used.

Shellac dries a lot faster than poly.

Big NO to just plain shellac or polyurethane. Both are going to be too slick! Sure, for the sides and bottom, I would go polyurethane, but I would want an epoxy with some grit in it for the top where people are going to actually have their feet. You could add grit to the polyurethane too, but it won't last as long as epoxy.

If it was me, I would coat the whole thing with clear epoxy and then finish the top with grit added epoxy. You can buy bags of grit on Amazon to add to clear epoxy or polyurethane. http://www.amazon.com/40202-Non-Skid...rds=epoxy+grit

As a Crossfitter(sic) you may just want to go the cheap route and paint it as the thing is going to get abused and tossed around.
You want it to have some grip on the top or somebody is going to eat it when hopping up, like the bedliner/rhinocoat/line-x
My two cents for what it is worth ;-)

You could also add grip tape to the top after finishing.

Yeah with this box, every side is the "top." I like the idea of Bellinger as well, but I wonder about the cost, the additional weight, and how will it will adhere to the word. I like the idea of epoxy with grit added, except I don't want it scratching the floor.

I'm in the aisle at Home Depot now. I think I'll look for cheap bed liner.

Wrong type of material to use a clear, easy to apply abrasive ressitent coating. Truck Bed coating would work. Clear marine polyester resin would work, but why?

Originally I was interested in keeping the unfinished look of the box. I've since decided it is not worth the trouble for what it will actually be used for. I went with some cans of Rustoleum bed liner, as I have a second project that calls for bed liner as well. I'll let everyone know how it turned out. Thanks for all the input, as usual.

Marine spar varnish. Add some sand to the varnish. Apply with rags.

I just used polycrylic on a project. I don't know how it will hold up long term but it went on well and it was two hours between coats with a light sand and tack between. Pretty straight forward.

http://www.minwax.com/wood-products/...tective-finish