Nostalgia

I miss some cities I have lived in more;
I hunger for them, long to walk their streets,
Hop on a subway, hike the urban core,
Enter the suburbs where the city meets
Its end, see all that I have seen before;
Yet there are those whose various retreats
I have no need to once again explore,
Nor any urge to sample those old treats.
What is the difference between these two?
How can I tell which cities I prefer?
I much prefer to show them off to you,
That you may see them as I knew they were
But notice them yourself as something new--
The others are an insubstantial blur.