When I started looking at colleges two years ago, Princeton and Yale were my two "reach" targets and come April I found myself blessed with admission to both but cursed with the wrenching choice between them. Though I never applied to Harvard, I imagine in the end I might have chosen Harvard over Princeton, for much the same reasons I ultimately chose Yale in my actual circumstances. Basically, like some other posters above mentioned, I just found Yale's campus, if not necessarily more beautiful, more energetic and the undergraduate vibe just more vivaciously intellectual. After several visits to each school, I liked the dining hall conversations with students better at Yale.
When I was doing my research, I stumbled into a couple of articles in the Daily Princetonian that capture my impressions quite succinctly. Both are by a well-known Princeton professor: Tiger? Bulldog? Tiger? - The Daily Princetonian
On reflecting on the differences between Yale and Princeton, he admits he likes Yale's "charged-up, intellectually tough atmosphere" where course sections "have more pop and sparkle than Princeton precepts". He call the energetic buzz of Yale's campus "exciting and bewildering." This is exactly what I felt and Yale has not disappointed.
On the topic of conversation, in the following article he bemoans the lack of good, intellectual conversation among undergraduates. He insists that " Princeton, as I have known it for 35 years, doesnít foster this kind of conversation as effectively as many of its sister institutions." The culture of conversation - The Daily Princetonian
Another quote is probably the most germane to this particular thread:
"Classrooms donít exactly resound with brilliant repartee before sessions start or after they end. Years ago, a brilliant Princeton High School student explained to me why she had chosen Harvard over Princeton, after taking a number of excellent courses at the University in her teens. Hardly anyone at Princeton, she remarked, said anything in elevators or stairways or corridors on the way to class, or while seated and waiting for instructors. She couldnít imagine going to college under such a pall of silence."
I suppose one might dismiss these comments as the musings of one aging, grumpy professor. But I personally noticed much of the same as I looked very carefully at Princeton.