I am a second-generation Dartmouth alum who graduated in the 90's. First, congratulations to your daughter. Whether or not she chooses to attend Dartmouth, it sounds like she has worked hard and done well, and I'm sure you are very proud of her.
Second, I will say that I loved my Dartmouth experience and have a deep and abiding fondness for, and loyalty to, my college. It is a beautiful campus, the quality of the facilities and the staff are extraordinary, and it prepared me well for life. Many of my classmates have gone on to do amazing and wonderful things -- there is no "stereotypical" Dartmouth graduate. If you google a list of Dartmouth alumni, you will see the diversity of careers and the level of success they've attained.
Having said all of that, I will not deny that Dartmouth has had a long-standing and deeply-entrenched problem with alcohol and the Greek system. It was there when I was a student, and I'm sorry to say that from my understanding, it remains an ongoing problem. However, I would emphasize that I personally did not experience this side of life at Dartmouth, other than as an occasional observer, nor did MANY of my friends. Yes I attended frat parties and drank, and I belonged to a coed house for a couple years, and I heard plenty of unpleasant stories about what kids got up to after hours in the frat basements. But many, I would say the majority of us, exercised good judgment and restraint. This was a small part of my life at Dartmouth. My focus was on my studies, my part time job, my community activities, and my extracurriculars.
I think my "partying/drinking" experiences were comparable to those of my friends who attended, for example, UVA, William and Mary, JMU, Mason, BU, Middlebury, Cal, UMass, Mt. Holyoke, and many other schools. That is, these issues are not unique to Dartmouth, but they do get a lot of press and I'm sure there are schools were drinking is far less prevalent. I think you should prepare your daughter to deal with these issues no matter where she goes. If she has a strong sense of herself, is not the type of kid who is unduly concerned with "fitting in" or "being cool" she will find a large group of like minded people at Dartmouth and will be able to avail herself of the wonderful opportunities it provides.
Finally, I will say that the press loves a good Dartmouth story. When I went there, Dartmouth had been getting a lot of bad publicity based on the conduct of a few students on the Dartmouth Review who tore down a shanty-town anti-apartheid protestors had erected on the Green. Everyone said, "how can you go to that conservative, racist school." They missed the salient fact that there were students there passionate enough be protesting against apartheid to begin with. I arrived at Dartmouth and found that those folks, not the handful of Review staffers, were the dominant voice. I think if your daughter attends she will find a campus engaged in a lively dialogue about gender roles, alcohol abuse, and similar issues of the day.
Here is an interesting link which will provide an insight into the diversity of careers Dartmouth women have followed:
http://dartmouth.org/greenways/program.html