Final polyurethane on refinished hardwood floors: oil- or water-based coatings

[Savannah_H]

I'm a first-time homeowner tackling my initial major DIY home improvement project: refinishing the hardwood floors in the living room and hallway. I've done plenty of research and feel confident about the sanding and staining process, but I'm getting conflicting advice about the final polyurethane coat. For experienced DIYers, what's your proven method for applying a smooth, durable finish without brush marks, bubbles, or dust nibs? I'm particularly interested in whether you prefer oil-based versus water-based poly for durability and ease of application, and any tips on controlling the room's environment. How many coats did you find necessary, and what was your sanding technique between coats?