We finally completed the floor refinishing on the 3 rooms and hall upstairs! It took a lot of time, but it was worth it.
Below: ripping out the carpet - tack strips and floor staples also had to be pried out.
below: the bare floor with old finish and stains.
Below: in process - the floor after sanding.
Below: completed floor. We used a water based sealer and 3 coats of water based varnish. The water based product has MUCH less fumes than the oil based stuff.