if you\'re going to throw a quote/saying in there, go with a famous poet/writer or relate it to your favorite book or childhood story. while the grateful dead or other bands have inspiration lyrics that people who love the bands can relate to, not everyone is familiar with that whole mentality.
I was thinking the same thing. Use quotes sparingly and stick with ones that everyone, or most everyone, will know. Also, it is best to use a quote as a starting point, give credit to the person who originally said it, and then connect it to a personal story that has to do with your life and school and the whole experience. Personally, I would recommend Thoreau. He gives great advise on how to live life and be free. Here are some of my favorites:
As long as possible, live free and uncommitted. It makes but little difference whether you are committed to a farm or the county jail
Rather than love, than money, than fame, give me truth.
If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music he hears, however measured or far away
True friendship can afford true knowledge. It does not depend on darkness and ignorance.
OK, I could go on forever! (I was a huge Thoreau fan when I was in school.) He has so many quotes that could go with a theme of people being free, being unafraid to be who they are and not who everyone wants them to be, and searching for truth above all else in their future experiences. The best graduation speech I ever heard was at Quinnipiac and it was all about those ideas of finding and making your own experiences. Only time I actually listened to a graduation speech!