Without a doubt it would be Christmas time. Some of the best memories I have were of Christmas's back when I was a kid, and all of the family was together. Now that years have gone by, the family has scattered out across the states and Mom & Dad are gone, it brings back very special memories of the fun and joy we had when we were all still together as a family.
That and I now have some great memories of Christmas time when all of my kids were just little ones themselves. Time passes to damn fast!