Drive it first. The worst hills are often tiny things of no consequence that go straight up. If I was still young and healthy, I wouldn't want to strip the adventure right out of it. These days there is so much information out there you can at least get people to comment on just about any route. One thing that doesn't work is asking locals who probably don't cycle.

In many cases it might still be preferable to do the steep route if it just had one or two bad bits. Walk them, or maybe find a shuttle. I wouldn't give up hundreds of miles of Pacific breezes to go inland among logging trucks and clearcuts.