Resurfacing hardwood floors in a rental house

[Chris T.]

I am resurfacing hardwood flooring in a couple of houses. These are for rentals. I have read some past forums that a couple of coat of polyurethane is the way to go.

Anyone has any recommendations which brand to use? 

And would you go with a lighter or darker color stain? I would assume light color stains as it hides the scratches well, compared to the darker ones.