The Maverick Philosopher has a post on why he likes parties:
I like parties. I derive considerable satisfaction from not attending them. There is such a thing as the pleasure of conscious avoidance, of knowing that one has wisely escaped a frustrating and unpleasant situation. If others are offended by my nonattendance, that I regret. But peace of mind is a higher value than social dissipation -- which is no value at all.
I agree with him, but I think it's important to point out that parties and peace of mind are not mutually exclusive. Consider the example of Socrates.
So Agathon was getting up in order to seat himself by Socrates, when suddenly a great crowd of revellers arrived at the door, which they found just opened for some one who was going out. They marched straight into the party and seated themselves: the whole place was in an uproar and, losing all order, they were forced to drink a vast amount of wine. Then, as Aristodemus related, Eryximachus, Phaedrus, and some others took their leave and departed; while he himself fell asleep, and slumbered a great while, for the nights were long. He awoke towards dawn, as the cocks were crowing; and immediately he saw that all the company were either sleeping or gone, except Agathon, Aristophanes, and Socrates, who alone remained awake and were drinking out of a large vessel, from left to right; and Socrates was arguing with them. As to most of the talk, Aristodemus had no recollection, for he had missed the beginning and was also rather drowsy; but the substance of it was, he said, that Socrates was driving them to the admission that the same man could have the knowledge required for writing comedy and tragedy -- that the fully skilled tragedian could be a comedian as well. While they were being driven to this, and were but feebly following it, they began to nod; first Aristophanes dropped into a slumber, and then, as day began to dawn, Agathon also. When Socrates had seen them comfortable, he rose and went away -- followed in the usual manner by my friend; on arriving at the Lyceum, he washed himself, and then spent the rest of the day in his ordinary fashion; and so, when the day was done, he went home for the evening and reposed. (Symposium, 223b-d; trans. Fowler)
Socrates, the consummate philosopher, is the only one left awake at the end of a raucous party in which he has given a beautiful speech (outdoing all the other speeches) on love. He had gone eagerly to the party (though he had been distracted by something on the way) and had even dressed up for the occasion. Here we see Socrates as both the paradigmatic party animal and rational animal.
However, at least in my case (and perhaps in the Maverick Philosopher's case, too), I am too feeble a soul to be both; so I try to live up to my nature as a rational animal and leave the partying to others.