After reading about how novices should NEVER use drum sanders & walking on quite a few wavy floors in my neighborhood, I attempted to sand my 100+ year floors on my second floor with an orbital sander & wasted 3 vacation days doing this. I decided to suck it up & rented a drum sander. They're all done. I followed the entire progression of grits & just got done buffing them.

I'm thrilled. They are gorgeous. I've put all kinds of light on the floors at all different angles, and the few swirl marks or unevenness I had are now gone. I patched the worst of the boards with wood salvaged from another old house. From reading about it, It seems like wood putty will just pop out, so the smaller gaps & such I'm leaving. The floors are still full of enough dings to have old house character, but they're just stunning. And now I'm terrified to stain & seal them.

We've got a lot of darker, aged trim & paneling downstairs. The same for the stairs. When it comes time to do the downstairs floors, I'll use a darker stain so the contrast won't be too stark. If we can afford it, I'll hire our local old floor guy to do them.

I hear so many warnings about not staining pine floors, but if I just seal them, I think it's really going to look strange next to the darker woods of the stair treads & banister. Most of the trim upstairs is painted white, but I do have two mantles that are the original varnished wood. I'm not painting over them.

My other issues: we're living in the house with a small child & cats that can't be moved. I can leave with my daughter for a few days here & there, but we can't afford to move out for more than that. I'm going to move the cats into the farthest rooms away with the most airflow. That means oil based sealers are out. I was interested in the Rubio, but the closest dealer is 200 miles away. The local flooring guy I talked to mentioned Duraclear. Right now, I'm leaning towards the Bona line: using the Amber Seal & the Mega. We plan on using a satin.

What should I do? If I stain them, will they look like crap, even though I've gone to a lot of trouble to make sure they're smooth? Out of all the stains I tried, the Miniwax in cherry looks the best. It's darker, but still shows off the beautiful grain of the wood. Or will the Amberseal give them enough color that they won't look odd meeting the dark wood of the stairs & wood spindles on the landing? We plan on applying wood conditioner before staining? Is this a good idea?

Right now I'm feeling overwhelmed. We love our old house, and we want to do right by it.

Old pine floors will darken some after they have been sanded. The old varnish had a brown color after it aged. The amber type sealers have a yellow type of tint.I always like to stain with a light brown stain and if you "pop" the grain by dampening the whole floor with a coat of plain water, it will hide most all the fine scratches, if not all. Just let the coat of water dry thoroughly before the light stain.
After you stain the floor to get the right color the clear coating will not change the color. A stain will dry usually in three to 4 hours and acts like a coat of seal. so the first coat of finish is ready for application after buffing with a purple pad, after the stain has dried.
I like a stain because the color helps to anchor the architecture, just like a white or light color is good for a ceiling.
With a light brown color I think that a conditioner is not necessary. Test a color sample in a closet if you have one, or under a rug or runner, so you won't need to sand off the sample. Use patching wood if you have some. Pigmented stains vs. dye stains are best on pine. Most stains have a combination, but the red stains usually have lots of pigment because the red dyes are fugitive, which means that they fade rather soon in bright light and pigments are longer lasting.
Old varnishes used to come only in Gloss. I like satin.