I love the value on Seattle.
My problem with GB is that SF game, that's the real problem. It's really hard for me to see them winning that game—although I do expect the game to be close.
That said, if they get through SF I do think they can beat Atlanta in ATL. Honestly I kind of expect them to. So, to me, what you're really doing is asking, is the number you're getting now to win the NFC > the ML number you'll get at SF.
I agree you can't put that ATL/GB spread much over -3. I think at worst (injuries notwithstanding) you get Atlanta -3.5 or -4, but that's assuming the books want to take a stand with the Falcons.
More than likely I think you get Atlanta -2.5 to make sure they balance the action out a bit, because they'll get GB money no matter what the line is.
Given that, there's no way you get a +400 ML in that game so the answer would be yes, to me there's good value there.