I lived in Sydney for 8 months and Brisbane for 4 years. When thinking back, both feel like a distinct part of my life to a surprisingly equal extent. Maximizing the number of distinct phases in your life seems to me to be important in making it seem longer.
It points at another approach to getting the most out of life: change as much as you can. Maybe once everyone in your family had had a few of those magical Christmases it's time to look for something else fun.
Very good point. A visit somewhere entirely new for just two weeks feels like 3 months of comparable memories to the two weeks in my regular mundane life.