Thank you for all of the advice in this thread. The Denver to Seattle trip is over, and here is a brief summary:
Around 3100 miles for a total of 52 hours driving, and $300 spent on supercharging.
As suggested in this thread, we went out using 84 through Oregon, and then came home on 90 and 82 through Washington. That worked out well, except after so long driving on sparsely used roads, it was a bit of a surprise hitting the traffic north of Portland, which pretty much lasted all the way through Washington to our final destination at Sequim.
Camping was good at Sequim Bay State Park. If you’re in the area, showers are now free. The kid and I went into Port Angeles and played with marine life and on the little beach there. We also went out the Dungeness spit. Missed Olympic National Park, based on the reasoning, we’ve seen mountains, just saw a temperate rain forest the week before, and wanted a day where we could sleep in, instead of rushing out to get in line.
After that we spent a night in Victoria, BC, where we ate at a brewery, walked around, and went to the natural history museum. My kid really wanted to go to Canada, so we did.
Then went to Seattle, and did the Chihuli museum and the Pacific Science Center. Those were both a big hit with my kid, which is about all that counts. Then she got stuck in the giant climbing playground under the space needle, because she wouldn’t come down the slide.
A few praises and criticisms of the PNW. The Seattle toll roads let you join on a license plate only temporary basis. It was easy, and saved me a few dollars on the 520 bridge. Not that big of a deal for two trips, but a nice consideration if the stay had been longer.
Seattle drivers are weird. I thought only small town Boulder drivers had such a pack mentality they’d all line up in one lane, even if they actually wanted to be in a different one. Multiple times there I’d see drivers all get in one lane at a light, then as soon as they crossed the intersection, they’d move around to whatever lane they actually needed to be in. I kept waiting to see if there was a reason, but I never could figure it out. Same as in Boulder, but bigger city and more cars.
Idaho, Utah, and Wyoming may be ultra-conservative states that worship oil, but they do have quiet roads. The roads in Washington and Oregon are too loud, and I’m judging them on it.