I need to go to bed, so this will be much shorter than it could be. My friend Ryan and I rented a pair of U-Sand (random orbital sanders) from home depot and sanded down 1000 square feet of hardwood. We have VERY sore necks from man handleing these machines that wanted to go their own direction and from leaning over to see what we're sanding. If it looks good after stain and sealing it will be totally worth it!
Here's a before and after of the living room: