We tried to sneak “You Shook Me All Night Long” by AC/DC through the school censors and they told us it was too full of double entendre, yet that was the kind of music people in my graduating class listened to. They shot down several songs that had meaning to my class both from the then present day (1989) and songs from before our time which were still well appreciated…the kinds of songs you’d hear whenever you went to a party or a dance or any gathering of your classmates, the songs that would cause people to turn up the radio if you were riding in the car with them. A song should 20 years from now remind you of high school. Because we had such facists in control of our school, we ended up with the love theme from St. Elmo’s Fire, most likely because some of the weepy bitches on the yearbook committee became teary eyed when they saw the movie or some bullshit like that. Was anyone playing that song or singing that song at our 20 year reunion? No, they were all singing Bon Jovi, Motley Crue, Poison, AC/DC. Songs that could have been a great class song. A class song in my opinion should epitomize the class. I can’t say what your high school experience was like, so it’s impossible for me to pick a song for you.
Now, if I’m just going by your description of something not(?) too heavy, but good rock, older like 90s, if you don’t want to go to AC/DC which is essentially the definition of just good balls out rock and roll that you don’t really have to think about, you can go to the opposite extreme and pick a Nirvana song…also really good rock and roll, but imbued with a lot more meaning. I think the best thing is to try to think of the older, harder songs that everyone in your class seems to enjoy, it should become fairly obvious if you do that.