I have a 4' x 8' loft in my barn. I dropped a sheet of luan over the existing wooden barn floor and trimmed out the perimeter with some quarter round molding I had left over from a remodel project. That's it, nopaint or finish. I scrape the luan daily with a garden hoe, and occasionly sweep around some chalk (Belgium White) to help keep things dry. It's slowly turning white in color, looks great, and is easy to clean. Good luck!
Thinking about it some more, my other lofts have smooth plywood floors which I painted with multiple coats of a semi gloss paint. After a few years of scraping, most of the paint towards the middle has been scraped off. Bottom line, if your floor is reasonably smooth, I wouldn't bother painting. Luan is a cheap, smooth surface that scrapes easy. If you eventually wear thru it, just drop in a new sheet.