I did this marathon for the first time this past fall!
I must say, it was a prettier route than I had expected.
As regards to the "killer hills", I think that you'll be ready for them following the P-fit training schedule. Doing the training runs up/down Leif like the group does on occasion will get you ready.
I think the one killer hill along the Seattle route I can think of is such because of where it is....somewhere around mile 16 or so if I remember right. But you can look up the profile on the seattle marathon website and see exactly where to expect it.
I have to say...I love hills and do better with that kind of course over a flat course. That being said, I think you'll still do fine because it's a gradual incline up....long yes...but gradual is better than San Francisco style UP!!
I had run Portland 6 weeks prior to running Seattle last year. So factoring in fatigue, the hills, and everything else (like long portapottie stops), I still managed to finish only about 12-15 minutes later than Portland's finishing time. So, I think you'll do fine!
I think I'd be more worried about the weather up there....I got lucky last year, it didn't rain

Good luck and Happy Training!