Times have changed and latex is a better and more durable choice than it used to be. I've painted plywood floors, after knot-filling and sanding (with an industrial sander), put three coats (two when it was my place) of urethane on top and Bobsyeruncle. Lasts years and years, even with fairly heavy traffic, and if the surface starts looking a little scuffy or dull, put another coat of urethane on 'er.

One of the (few) practical crafts I have done a lot of is painted canvas mats, usually about 24 in. by 30in., but I've made a couple as large as six by eight feet. I use ordinary interior flat latex for basecoating, decorate with acrylic (sometimes mixed with household latex), urethane coat it two or three times and there you are. I usually give people a sized to fit piece of rug underlay to go with - makes it softer and prevents slipping. Those things are durable. There's one I made 22 years ago that's been on the floor in front of the owner's sink all that time. He says he's re-coated with urethane twice and it looks perfect.