For what it's worth, I rooted for the 49ers in Super Bowls in the '80s. I really, really enjoyed the one when they utterly destroyed the Elway Broncos.
I think I rooted for them in the one after the '84 season because the Dolphins had beaten the Seahawks in the playoffs, but I actually liked the 49ers too. There was just extra beef for me against the Dolphins. Now that I'm not in early adolescence like I was at that time, and so some of the bitterness has passed, I think the Seahawks and Dolphins were pretty close as teams in '84, and it's not such an injustice that the Dolphins won. In fact, considering that that was the year of Curt Warner's big injury, it was kind of great for the Seahawks to have done as well as they did. And the Seahawks winning the divisional round in Miami after the magical 1983 season was an upset. I knew they could do it, but I also knew my dad was right to have a little talk with me about the season after the Seahawks beat the Broncos in the wildcard game and then had to go to Miami for the divisional-round game, to get me to control my expectations.
I would like to point out that at the time, the Seahawks were in the AFC West. Because I grew up in the '70s and '80s, I still have more residual dislike for the Raiders and Broncos than for the Seahawks' current division rivals. But I will concede that many current 49ers and Rams fans are at least as irritating as Raiders fans. Man, the 49ers trolls that hang around the Seahawks-fan site with the stupid-ass name (the one that's part of SB Nation) are worse than the most annoying nine-year-olds on the school bus when I was a kid.
I have also rooted for the Broncos twice in the Super Bowl. Once was back after like the '77 season or so, when Craig Morton was the Broncos' QB. It was too early for me to see the Broncos as a loathed division rival (it was the Seahawks' first year in the AFC, the team wasn't a contender, and I was in Maine, where there was precious little coverage of the Seahawks, so it took me a couple of years to get into the rivalries, except the one with the Raiders, because I disliked them already), and I wasn't so much rooting for the Broncos as against the Cowboys. And at that point, the Broncos were the only team that could possibly have stopped the Cowboys. As I recall, I watched very little of that Super Bowl.
So since we're on that subject, I also rooted for the Steelers in those Super Bowls in the "Steel Curtain" era. I also wrote to Steelers players for autographs, and I used allowance money to buy frames for the autographed pictures I got back from Lynn Swann (it was an oversized postcard of him, and he really signed it too) and Terry Bradshaw (I wrote to him c/o the Steelers in Pittsburgh, and he sent the autographed pic back from Louisiana), and those were up on my wall with the autographed pics of Seahawks players.
Honestly, I had nothing against the Steelers until after the 2005 season. Now of course, their name has been changed to the Pittsburgh Title Stealers and they can collectively kiss my hairier-than-I-wish-it-were ass. And I sincerely hope Bill Cowher has multiple episodes of explosive diarrhea every day for the rest of his life (and may he live to 95 that way!).
And yes, after the 2015 season, I rooted for the Broncos, first against the resurgent Cheatriots in the AFC and then in the Super Bowl, a little against the overrated Cam Newton, but mostly for Peyton Manning. He was terrible that whole season, but I thought he deserved more titles for how beyond-great he was in his career, and how he completely changed the game. I still dislike the Broncos, but I was glad Manning got another title and then did the right thing and retired.
