For this type of lingering, the proper drink is needed. Here, coffee comes up short, as the longer you wait to drink your coffee, the less desirable it becomes. And generally you've reached that point in the evening where you've moved on past wine, and having moved on, there is no going back. Certainly scotches and brandies can come into play, but for many people's pallets, these are a bit harsh. To Portugal of course, and the wine which draws its name from the city of Porto.
Port is much sweeter than regular wine.
This is due to the brandy which is introduced into the wine before the fermentation process is complete. The brandy kills the yeast before it can eat up all the grape's natural sugars, hence the sweetness. Older ports can have a good amount of sediment in them, and may benefit from a decanting. If you are forking over the money to buy an older port, you either know what you are doing, or you are hopefully smart enough to ask the wine shop proprietor for his suggestions on decanting. As with wine, once uncorked, port's flavor will begin to head downhill.