Just a warning—we did a dark walnut stain in our house and even thought it looks beautiful, part of me has always regretted it. I would only do it if you have an ABUNDANCE of natural light, otherwise the room can look way too dark. It also shows every bit of dirt, leaves, dust, whatever, that gets tracked in. We said, "Welp, we'll just have to keep it EXTRA clean" but you can imagine how that has gone. Personally, I like a light or blonde wood look, something like the "golden oak" in the chart above. It's versatile and timeless, two things that are important when you're talking about a job as big as floor refinishing.

Also, I would leave the beams the way they are, or stain to match. Don't paint them! It's irreversible, and natural wood beams are such a part of a home's character. May be my midcentury bias showing here, though.