US-2 Westbound in WA - Stevens Pass Summit to Seattle

It's a beautiful and well maintained highway, and you will have no issues.

You might try to avoid traveling on Sunday afternoon, as there can be lots of stop and go traffic through the small towns between Stevens Pass and Monroe. Highway 2 was also closed due to forest fires several times this year just West of Leavenworth. Get on the WA DOT site for current information when you are traveling.

WA DOT

Several miles on the east side of the pass are divided highway. The west side starts off with a 4 lane, undivided section. At the bottom of that grade is a U turn signed 40mph.

Currently Google Maps streetview shows a 2 lane section in the upper grade due to work on the cliff face. I'd check WSDOT for the latest on maintenance work around the pass.

There's an upper curve that might be visually unsettling. It's a gentle curve, but as you approach it you have a big valley in front of you with just a jersey barrier to keep you from flying off into the air. But if news is anything to go by, it's the lower part of US2 around the towns of Gold Bar and Sultan that's the dangerous part. There you have more traffic, including a lot of turning, that can result in collisions. In the upper part you have to be careless to get into trouble.

We run 2 most all the times we go east and back we have no problems with the road, it is 2 lane from the bottom of the down grade to Monroe Wa. Truckers use it, I see no problems for you, slow down and enjoy the view. The up side from Levenworth to the pass is the worst of the trip.
Highway 2 a crossed the north is the way we like to go when we go to New England, the small towns along the way supply the stops you need to make and most have great camp grounds.

The actual mountain pass section has a couple of turns in it but it's a major multi-lane highway at those points and only a few miles long. After that it turns into a scenic two lane highway that's perfectly pleasant to drive because the hills are very gentle - you'll probably have to give it a little throttle to keep up to speed in most cases. Also the road is kept in great repair. It is curvy but they aren't tight curves as the speed limit is mostly 50+ mph.
It's truly one of the most beautiful routes in Wa. State.

Big Mac, yes it's curvy and 2 lane, but it's a gorgeous drive! I would say its 2nd gear in some places, but mostly moderate braking out if OD.