I really only look at strength of schedule in the playoff weeks and when choosing between 2 equal players. As we all know, some defenses can totally rock one year and totally suck the next. Although some things can be relied on I think. Pittsburgh is going to be tough as hell to run on but I still think their pass D is suspect even after adding Polamalu. Tampa is just going to be plain tough all around. Arizona is really going to suck.
Take a look at the top 3 backs that are almost a consensus 1,2,3 and interchangeable anywhere...Ricky, LT, and Portis.
These guys are all great and I don't care what the entire schedule looks like overall, they are going to get their yards and scores. Barring injury, no one can blame you for taking any of them 1st, 2nd, or 3rd. So with that said, IF I get to the playoffs, which one is going to help me the most.
LT faces Green Bay, then Pittsburgh - I really do not want to have a RB going against the Steelers on Championship week.
Ricky faces Philly and Buffalo - Philly was pretty good against the run last year, but against Buffalo he did pretty well, even that first game was decent.
Portis faces Cleveland and Indy - (27th and 20th against the run last year) Portis played pretty well against Indy last year 88 yds and 2 TD's.
After considering that, I probably would take Portis, then Ricky, then LT just to break up the tie.
Overall SOS is not that important, unless the schedule is super difficult or super easy (e.g., people are undecided about Maddox, well the Steelers don't play anyone ranked greater than 12th against the pass last year). I mainly look who the playoff teams are when trying to decide between a couple players.