Sealant today. I used a paintbrush to apply the sealant around the edge of the floor, and then Barb filled in the center using a roller. Today we covered about 75% of the floor; the remaining 25% is occupied by the furniture, including my overstuffed bookcases. Once the floor has dried, we'll shuffle around the furniture onto the floor we've already done and finish up the rest.
Once the floor is completely done, that will end the stuff we can do ourselves. Time to start looking for a contractor!