Your institution probably has a few days scheduled for fun events around campus. If any of them interest you, and you're able to obtain tix, go to one! Rutgers transformed its main library into a 'club' to commemorate the long, lonely winter nights spent in its halls; how fun is it to see your haunt with a temporary makeover?!
2. Have a plan
However you're usually accustomed to spending your time on campus, scratch those activities, because now is the time to LIVE, baby. Use those facilities if you're dorming to their fullest extent. Make sure every day has at least three activities for you to check off your to-do list, be it visiting a building you've never had the pleasure of taking a class in, or taking a picture with the mascot that is SUCH a touristy thing to do, but you'll appreciate it in a year's time!
3. Stay on campus
If you are asked to vacate school grounds as per official instructions, then by all means, please abide by those directives. Otherwise, try to stay on-campus if you can, because it'll be the last time you'll have the luxury of living in your college town as an actual undergrad. Plus, it's so much simpler and safer to know your crash pad is just a few minutes away after a (responsible) bar crawl rather than having to get in a car and drive 20 minutes home.
4. See your friends
...But only the ones who have genuinely been there for you. What they say about losing college friends after graduation is true, but you'll come to realize that only people worth staying in touch with will do so. Sure, hang out with that fair-weather friend who only wanted to party with you but would magically disappear if you admitted personal struggle, but do you really want one of your last memories that you'll cherish forever to include that person?
5. Reflect and appreciate
If you can, send thank-you notes to any professor who made a difference for you, or any administrator who has done the same. Personally, I would send such notes after every semester, regardless of what my final exam score was. One lesson I realized this year is the hidden collective efforts of people's dedication in an individual. No matter how big or how small, people will shape you in ways you won't expect. That professor who consistently gave you Cs and gave you wishy-washy feedback during office hours only motivated you to work more diligently in the class -- so thank him! Thank that dean who always allowed you to drop a class riiiiight after the deadline had officially passed, out of the goodness of her own heart. Your hall's cleaning lady probably had to clean up some unsavory stuff in your time there. Thank her. People enjoy appreciation, and the right people aren't nearly recognized enough.
And I would hope that this is a given, but please, PLEASE attend your ceremony, regardless of a high-profile speaker. Call me a cynic, but graduation is one of the few instances in a person's life where nearly everybody involved in the ordeal is truly pulling for your success as an individual and for your future...so have fun!