As donn0128 has indicated there are other relatively flat and more interesting and scenic routes such as: turn off I-84 at Ontario, Oregon onto US20, about 260 miles to Bend, then either north on 97 to connect with I-84 to The Dalles (a little crooked in spots), then into the Columbia Gorge for 83 gorgeous miles to Portland, or if you're already bored by the gorge, continue on 20 from Bend to the junction with SR22, then to I-5 at Salem.
2001 Chev 2500HD 4x4 6.0 reg cab long box
2004 Lance 1010, 130 watts solar, Happijacs, EU1000
2001 Arctic Fox 25' fifth wheel, 175 watts solar
Looks like plans have changed a bit. Now going up to Seattle for a couple of days. Trying not to have to drive the MH all the way would like to day trip w/ the toad.
Would it be better (flatter) to take I-84/I-5 or I-82/I-90 from Boise. I know either way we'll problably have to cross Cabbage Hill at Pendelton but wasn't sure after that.
Flatter? Take I84 to Portland. Don't forget you have one nasty hill on I90 if you choose that route. Personally I think it is worse than coming down Cabbage Hill. It will be way longer though. Stay in Portland and drive to Seattle. You will thank yourself. Even though it is roughly 3 hours of driving, the traffic in Seattle area is about the worst you will ever see. Not a lot of fun driving a big rig.