Rather than sanding and finishing a floor that has minimal use, it may not be necessary to fully sand and finish a floor. If the wear isn't all the way down to the top of the tongue and the scratches are minor, going back over the floor with a light abrasive and a coat or two of finish might be the appropriate solution to help preserve and extend the surface of the floor. It's a relatively simple process and doesn't have the same intensive involvement as sanding nor expense. This is  recommended after a few yrs of wear on a new finished floor, so it may prevent a homeowner from going through the whole sanding process later on.  One thing a homeowner should be aware of is cleaning. One should never use harsh cleaners, waxes or oil soaps. If one puts a product on the floor as described above , it may not allow an additional coat of finish to adhere to the surface. The only thing that should be used to clean is National Wood Flooring Association approved products. If your not sure of what's approved, Vinegar (1/2 cup) in a bucket of water and damp mopping should be all the cleaning necessary to get up most spots and spills. Lastly, the best maintenance one could do for a floor, is keeping the dust and dirt dry mopped. Dirt can act as sand paper to the surface of a floor. Investment in a good wide dust mop, used every other day or so can reduce much of premature wear.