Staining brings a new element of ideas with hardwood floors. In many cases colors can be changed over the years providing the existing stain is not too dark or hasn't fallen into any open side and end joints during the original staining procedure. This will be visible if you're attempting to lighten a floor in later years. Another key would be the thickness of the flooring as changing a stain requires more material to be sanded off the floor itself for a successful color change. Please see some of the stain colors shown below for reference purposes only -

Having hardwood floors stained should only be considered with a seasoned professional as mistakes can lead to higher costs and inconveniences. It's imperative all cleaners, stains, and finishes be removed from existing hardwood floors to insure a satisfactory new stain application. Without doing so, a non-uniform result will occur. This is why we strongly suggest someone familiar with this type of application for the work. They'll have the experience and know how and what do to in special situations. Potential red flags may also be discovered that will prevent a successful application and may have nothing to do with the condition of the floor itself, but its surroundings.