I was a member of a sorority during the 1990's at a small liberal arts college where I lived in a dorm, but the sorority just had a meeting space, not a house to live in.
These are some of the pros with 15 years of hindsight:
1) Opportunities for leadership. As a member of my sorority's executive council, I developed skills that are crucial to the business world. These included time management skills, delegation, the ability to verbalize my ideas in a group setting, responsibility, etc. Even before I joined the executive council as a junior, there were always committees you could join to contribute to different projects and events. This also helped me to overcome my inherent shyness which would have really held me back in my career as an adult.
2) Charity: I believe all Panhellenic Greek organizations have official charities that they support. I did not go to a high school that required volunteer hours so this was my first introduction as a young adult to the importance of contributing my time and efforts to a good cause.
3) Sisterhood. I grew up with two brothers and always wanted a sister. I can honestly say that the women in my sorority became my sisters. Four of these women are still my best friends today, and have supported me through every step of my adult life. Studies have shown that people who are "joiners" and belong to some type of community organization are less prone to depression etc. There was a sense that you were accepted much like being in a family -- the way that home is where when you go there, they have to take you in, my sorority acted as that for me during my college years.
4) Team spirit: much like joining a sports team, Greek organizations provide an opportunity to bond with your "teammates" or sisters through various competitions (we had singing competitions, Greek Week athletic events such as flag football, synchronized swimming competitions, etc). I always had a sense of belonging and never felt isolated. I think in a world where students can now spend their lives locked in their rooms with their computers and end up feeling very alone this is even more important.
5) A life long network. As an alumna the opportunities to join alumni clubs exist all over the world. I try to make it back to my college campus for our sorority's Founders' Day each year. Some of this is old fashioned -- formal teas, lots of singing together -- but I enjoy these kinds of activities and they are much more "clean cut" than the stereotype that Greek Live often unjustly receives.
Granted, there was a lot of partying, and the things I have listed above can also be found elsewhere. But I found it incredibly rewarding and I would not change a thing about my Greek Life experience.
I hope that helps. It is not for everyone but if a young person is inclined to look into it I think there can be a lot of benefits.