I second the trimming. I can always tell when my nails are too long (right now, actually!) I generally keep mine polished, with a decent topcoat because I have a tendency to rub the surface of the nails of my big toes against the boot and get some deep scuffs in the nail. I've found that my topcoat holds up better than the nail and my polish doesn't wear off any faster than one would normally expect.
As a side note, I have a coworker that has a sign that says "toenails are for sissies"... she runs marathons and missing a few toenails is normal for her. Personally, I prefer mine intact.