My undergrad (Rice) didn't have a greek system, which I thought was awesome. Everyone drank together for the most part.
Where I'm doing grad school (Cornell) the greek system is huge, but as a grad student it doesn't impact me for the most part. However, there are a few bars that during the school year tend to be full of bros and sorority girls that I won't go to. This place is so much nicer in the summer but all the undergraduates are coming back next week and that sucks.
And man, our softball team (Mechanical Engineering Ph.D. students) was so close to winning the summer championship, against a frat team. We (visitors) had an 8-5 lead going into the bottom of the last inning, but just fell apart and gave up 4 runs. It was brutal - I wanted to win that one pretty badly.