Song choice??

i am singing at my graduation this year and i have no clue what song to sing! i need it to be appropriate, and i will take any suggestions as long as they aren't "graduation" by vitamin c. so far, i have though "beautiful disaster" by kelly clarkson (although it has nothing to do with graduating) and "let it be" by the beatles. I want it to seem meaningful and to have reason behind it. please help!! thank you!