You always want the #1 seed, no exceptions.
That's like saying that you always should punt on Fourth and One at midfield. It's what everyone believes, but statistical analysis after statistical analysis show that you are no worse off going for it (see, for starters,
The Hidden Game of Football by Bob Carroll, et al.).
Facts are annoying things, but I had a few minutes this morning, went back 15 years and analyzed what happened to the Number One seed in the two conferences (total of 30 data points):
--Ten of the 30 were one and done, losing in the Division Round (as we painfully recall is possible)
--Seven of the 30 lost their Conference Championship Game
So, over half the Number One seeds don't even make it to the SB.
--Seven of the 30 lost in the Super Bowl
--Six of the 30 won the Super Bowl.
So, based on these data, there's a 20% chance of winning the Super Bowl from the Number One slot, but an 80% chance of winning it from another point on the food chain. There's also less than a 50% chance that you even get to the Super Bowl (43%).
All things being equal, sure, I'd like to be Number One, but all things are seldom equal and so I do think there are "exceptions" since there are multiple factors that allow teams to do better from another seed, whether it's how a team's playoff opponents line up or whether it enters the Playoffs on a roll and with something to prove, as the Giants (ouch) did in 07 and the Pack did last year.
I'd agree with you in the case of a team like New Orleans, which has never won an outdoor playoff game and which seldom wins outdoors after December 1st unless it's playing in 40 or 50 degree conditions in the South; does anyone seriously think that the Saints are going to go into Lambeau and win in January when the average low temperature is in the single digits?