Something to consider:
When I chose my flooring (hardwood, tile & grout, etc.) back in 2004, I quite honestly had no clue as to what I was doing! :-)
Today, some 8 years later, I wish I had known more. My kitchen tile is basically okay, altho' places where I tend to do the most work sometimes show a darkening, I guess due to excessive contact. This is reasonably easy to erase, with an effort that I no longer wish to put out! However, the grout darkens more substantially and is considerably harder to lighten! Even my experienced regular cleaning service is at a loss!
While it may be totally impractical, it may be worthwhile looking into the "real bottom line," with connections to The Villages added to your mix!
I am considering calling one of the many firms which offer tile & grout care.,
when I have the chance!
SWR