For Clemson the non negotiables are:
USC - The Palmetto Bowl
GT - A very salty ACC rivalry. I always look forward to playing the Jackets regardless of the record
NCSU - The Textile Bowl. A much lower profile rivalry, but I make sure I watch it every year
FSU - Although they had not played much when FSU joined the ACC, it has developed into must-see TV and a ratings bonanza
I'm tempted to put Louisville here just because the past 3 games were amazing. However, those 3 games constitute the entire history of the rivalry.

Nice to have (it would be great to play one of these every year):
UGa - It's a shame we don't play this one more often. Athens is less than 90 minutes from Clemson. I'd prefer this be an annual rivalry, but it won't happen.
Auburn - Always a good game, but awkward in our house since my wife graduated from Auburn.
Notre Dame - High profile game. The last one was a nail biter.

I hate playing FCS games. I know it's a money thing for them and a tune-up scrimmage for us, but we do miss out on playing better games by doing so.