Ann-Marie, I'm not sure where and how you are planning to stay overnight, or how you will spend your time during the day, but I think your plan needs some adjustment. Your timeline is going to waste a lot of your time, I think. Pull up a map of northwest Washington, and see if this doesn't make more sense to you:
Note that Exit numbers on Interstate Highways are roughly the same as mile markers. So it's a good measure of distance by comparing the Exit numbers for where you plan to get on or off the freeway. You may find this website helpful:
http://www.wsdot.wa.gov/traffic/interstateguide/
Downtown Seattle is around Exit 165. The Everett area is only about 25-30 miles north of Seattle. It sits at approximately Exit 190 on northbound Interstate 5. Even with very heavy traffic, you'll be there within an hour or less. Morning traffic is heavier southbound, so I'd say heading against traffic you'd be there in a half hour.
The exit off I-5 for Highway 20 is Exit 230, so is just 40 miles north of Everett. Once you're on Highway 20, Newhalem is roughly 60 miles up the road. So the distance from Everett to Newhalem is just about 100 miles.
To my knowledge, there are no motels in the Newhalem area, unless you want to bring a tent and stay at a campground. There is a convenience store, a Visitor's Center, a public restroom, and a few things in the area to look at, but that's about it. There is no town.
My suggestion is to leave Seattle, and skip Everett (unless you have a reason to stop there.) Take Exit 189 west onto Highway 526, and catch the ferry from Mukilteo to Clinton, at the southern end of Whidbey Island. Explore your way up Whidbey, and be sure to see Deception Pass state park, and the incredible Deception Pass bridge.
You'll already be on Highway 20 at that point, so continue to follow it north. When you have a choice, take the left turn for Anacortes, Washington. Stay overnight there. Anacortes is a great place to see. It's on the water, has some great parks, interesting shops, many restaurants, and lots of places to stay.
Next morning, leave Anacortes and take Highway 20 eastbound toward Newhalem. It's only 75 miles or so. (Buy sandwiches and drinks for lunch at the convenience store there, but save it for a picnic you'll have shortly thereafter.) Don't stay in Newhalem, however. Continue on Highway 20 over the North Cascades, and stop for that picnic lunch at the Washington Pass Overlook.
https://www.tripadvisor.com/Attract...-North_Cascades_National_Park_Washington.html
Continue on to stay in Winthrop or Twisp, Washington. From Anacortes to Winthrop is about 150 miles, and will take more than 3 hours, but it is some of the most dramatic scenery in Washington state. There are many scenic overlooks and places to stop, so take your time and enjoy the drive. It's very worthwhile. Stay overnight in the Winthrop/Twisp area, and then make your way on to Republic the next day.
I think by making these changes you'll see much more enjoyable scenery, you'll make better use of your time, and you'll have a better time.
Dave
