I'm in the process of restoring nearly 100-year-old pine flooring (yellow pine, I think). The floor is now sanded, and the grain is beautiful. I will not be staining the floor. My questions are: How many coats of urethane should be applied (or dare I apply) to protect this relatively soft wood from wear and tear? I've been advised to use a satin-finish urethane; is this sound advice?