Fairbanks was a favorite interior location on our trip. We spent an extra day or two on the front end and it was amazing. From Fairbanks was actually the only time we saw the peak of Denali and we even went up in a plane for a tour of Denali.
Without hesitation I say 3 day Denali option. Rafting, a flight, your included bus tour day, hiking, resting and enjoying nature. It’s very nice.