Welcome to the cruisereviews forums.
We've been on a few group cruises. The amenities vary depending on the group and how it's set up -- for instance, some might include a private party, group dinner in one of the specialty restaurants, or onboard contests. Others might not offer anything except for a group discount. Your TA will let you know (if you don't already) of the amenities applicable to your group. Obviously, it sounds like you'll be watching the Super Bowl together!
Which cruise lines have you been on previously? NCL is a bit different in that every passenger is on flexible dining time, so be sure to make any reservations as soon as you can. Several members of our forum have been on your ship and can provide specific feedback on the ship.