My daughter had hardwoods under the carpets in a small house she bought. We had them refinished at the rate of $2.20/ft. The guy we used does refinishing for a living and he uses moisture cure polyurethane for the coating.
They came out great and have significantly upgraded the house. These folks patched all nail holes from the tack stips, re-set any "shiners" that they found, and overall did a great job. Took them 3 days to complete the 900 sq. ft job.
I would call a local realtor and ask them what value refinished hardwoods would bring. Folks that see my daughter's house are astounded that the 50+ year old original fllors are still there and look so good.