I was too young to attend the '82 NE game, sold my tickets to the '16 OSU win because I had to travel for work and was not able to attend any of the national championship games. I did actually make the trip to the '94 Indiana game, which many claim cost us the popular vote, though that wasn't memorable for any other reason.
I'm going outside of the box. The 1986 Pitt game. As a student walking out of Beaver Stadium at the end, everyone just had a sense of the enormity of the moment and we were about to be a part of it in some small way.
Honorable mention:
The 2006 (after the 2005 season) Orange Bowl was pretty cool. I was there as a guest of FedEx. Nice opportunity. My wife was pregnant. She was miserable.
The 2002 Nebraska game was jacked up. Gardner picked off that pass and took it to the house, I thought the (I believe newly opened) South upper deck was coming down.
The '87 ND game in freezing cold was memorable.
EDIT: '99 Arizona. We just destroyed them. Their internet fans made that win one of the most enjoyable. So much promise for the rest of the season. Yes, I was at the Minn game that year too. My first post-grad year with season tix.