First, the upstairs floors: these were the original varying width heart of pine floors supplemented with vintage heart of pine where needed. We had the floors professionally sanded throughout (we did not have the luxury of time to take this project on ourselves) and we elected not to stain them, given the beautiful wood tones already there. Although we had originally intended to use a polyurethane finish, a lot of research later we came to the conclusion that we had to use Waterlox. After our internet research, we mentioned our choice to a few subs who promptly confirmed the decision. I had never heard of Waterlox before, but I have to say, I may never use another wood finish again. Not only are we using it on the floors, but we've been using it on the stained wood trim throughout the home. The best part about Waterlox? No sanding needed between coats. The other huge advantage? Touch up of the finish is simple, easy and unnoticeable - not only for those dings made during the construction phase, but also for future wear, tear, and accidents.
The downstairs floors are the new wide plank oak flooring and we elected to add stain to these to give them a richer look. Because stain can be mixed directly with the Waterlox, it was a "two-for-one" deal in a single application.