Based on my analysis, the following bets provide the best value of any Super Bowl props. No one wants to bet them, because they offer little pay off and are downright boring. If you only care about winning money, though, read on...
All one-point XP attempts converted (-2000)
There were 4 misses this season in 192 regular-season games, same as last season. The last missed XP in the NFL post-season was in 2008, over 40 post-season games ago. The fraction of games in which one is missed has consistently been 2% for many years. These odds imply a miss rate of 5%, though, making this bet excellent value. Of course, no one wants to take this side of the bet--hence the value.
No successful two-point conversion (-420)
Denver and Seattle each attempted one two-point conversion this season in 18 games. Both failed. This year was not a fluke; in 2012, Denver was 1/2 and Seattle didn't try even once. These odds imply a >19% chance of a 2-point XP in this game. The history of both teams suggests that the likelihood of an attempt is closer to half that, and the overall success rate for two-point attempts in the NFL is a bit under 50%. This offers great value and slightly more palatable odds.
Last, but not least:
"Roughing the passer" not called (-160)
The odds on this prop are based on the average rate at which this penalty is called in the NFL. During the regular season, RtP was called 90 times in 192 games, exactly the same as 2012. I don't know the exact # of games in which it was called, but probably ~75-80. To simplify the math, call it 77. That implies 115 games without an RtP call in 192 total, or 60%. That's exactly the same as the implied odds for this bet.
However, some teams rough opposing passers much more than others. Also, some OLine/QB combos are less likely to be roughed. It's very clear from the historical stats that Denver and Seattle are both below average in terms of both committed and sustained RtP penalties.
2013 regular season:
Manning was roughed 0 times.Denver roughed opposing QBs twice.Wilson was roughed 4 times.Seattle roughed opposing QBs twice.
These suggest an average of ~ 2 RtP penalties / 16 games. The numbers were almost identical for both teams in 2012.
In general, roughing the passer is called less frequently during the post-season. Over the past 3 years (20 post-season games), it has been called 3 times (twice against Kaepernick last year). Again, the fraction of games with a RtP call has been nowhere near 40%.
Based on all of the facts I just recounted, I would put fair odds on this bet at about -400. At -160, it represents phenomenal value. It's yet another boring bet, but at least it lets you root for a clean game.