Those "safe" teams become less and less safe as the year goes on, none of them will go undefeated, and it's usually a loss to a crap team in games 7 - 10 that kill an undefeated season...
That being said, I still have the Patriots, the Packers (don't know how 'safe' they are), the Steelers, I've used the Cowboys and the Colts... but I did manage to squeak out wins with Seattle and Chicago, too....so that's good.
The next two or three weeks will be interesting.