I don't have a suggetion on fine quality mats, but what I do for winter is to get a couple on thick, rubber mats (fairly cheap) and place them in the front to keep all the winter mess from ruining the nicer mats (mine are just the standard ones)....your winters in Mass. must be as bad, probably worse, than in NJ. This makes cleaning interior rugs much easier in the sprring!
My Q didnt come with any floor mats, and I went to autozone and picked up a set of 4 for $30, and they match the interior perfect. I also have a set of rubber ones that I put over those in the winter. 30 is much better than 100 or so for a set of factory ones, but the factory ones are SWEET (that have the infiniti logo in them and say Q45)
If you don't have a lighter colored interior, for our winters here, we spread newspapers over our existing floormats.(you can change them often) Yes, I have newspapers protecting the floormats protecting the carpet. Ugg!