I can't speak for Detroit, but NYC is a good place to visit around Christmas, but it depends what you want from a trip. It's usually not super cold, and there's no shortage of places to go, things to see. Hotels are expensive, as is almost everything else, which is probably the biggest drawback.Agreed the Pinstripe bowl in NY and the Detroit bowls seem like punishment, not fun bowls. I would never travel to either location for a game in December.