I would much rather use 20 than 2 any day.
When you transit south on 97 from the border you start west on 20 at Okanogan, from there up into Loup Loup pass the road is a bit twisty up hill, but only for a short distance, the let down out of Loup Loup pass is easy and really good road into Twisp. 2 miles east of Twisp there is a stop sign at the bottom of the hill and a right hand turn to stay on 20. Twisp is the place to fuel up, and stock up on supplies at the Red Apple market, there really isn't much between there and Burlington.
The next attention getter is the river bridge in Winthrop. The west end of the bridge is a pretty sharp corner swing it wide. And enjoy Winthrop, there is great parking at the Red barn west end of town and a short walk back to main street. West out of Winthrop is the best part of the highway, gently rolling hills and curves and gentle grade all the way into Mazama, then the climb starts, 6-7 miles west of Mazama you'll be on the major pull of the highway with 1 wide sweeping switch back that places you on the side of the mountain, with a Oh My God view of the Methow Valley you just came thru. at the top of the pass there is a pullout and an over look. it's a must for pictures.
Out of the pass to the west there is a 5mile 5% down grade, don't smoke your brakes, then a short climb into Rainey pass, then a long 5-7 miles down grade but keep your speed down, there's no sharp turns for a while, then another down grade with a couple twisty spots, then no big deal until you get to the Diablo over look, Another must for pictures.
Then it is down hill again with a 90 degree turn onto Diablo lake bridge, then a little up hill pull and down again and a couple curves that are a slow speed curves, then it's middle river lake, another bridge, a slight up hill then the last slow going on a down grade with curves, then Newhalem, from there it is just a 2 lane highway to Burlington with Marblemount, and Concrete as speed traps.
Have fun it really is an enjoyable trip, just keep the speed down, don't smoke your brakes, take lots of Pictures.
On Thursdays the Seattle city light tour is a must do. (Newhalem) Boat trip on lake Diablo, power house tour, and a big feed/dinner camp style.
One more thing, going to Bellingham take Cook road off the second round about in Sedro-wooley to I 5, north. and save the Burlington traffic, the 20 to I5 intersection is a mess, even worse with a big rig.
