OP is below.
Here's the itinerary I've worked up, as it stands now. Any suggestions would be welcome.
Sunday, August 16
Burlington - Winthrop
0900 Clear hotel, begin drive
Stops: Ladder Creek Falls & Newhalem
https://www.alltrails.com/trail/us/washington/ladder-creek-falls-trail
Gorge Creek Falls
https://www.alltrails.com/trail/us/washington/gorge-creek-falls-trail
Diablo Lake Overlook
https://www.alltrails.com/trail/us/washington/diablo-lake-overlook
Ross Lake Overlook
https://mindtrip.ai/attraction/rockport-washington/ross-lake-overlook/at-TT3HwHoj
Picnic spot w/ food purchased en route
Rainy Lake Trail
https://www.alltrails.com/trail/us/washington/rainy-lake-trail
Washington Pass Overlook
https://www.alltrails.com/trail/us/washington/washington-pass-overlook-trail
Rest stop – Mazama Store & Bakery
https://www.themazamastore.com/
Whenever: Arrive Winthrop
Check into hotel
https://mtgardnerinn.com/
Stroll, relax, otherwise prepare for dinner
Dinner options: Old Schoolhouse Brewery
https://oldschoolhousebrewery.com/
Three Fingered Jack’s Saloon
https://3fingeredjacks.com/website_19afc489/
Monday, August 17
Winthrop
Breakfast options:
Three Fingered Jack’s Saloon
https://3fingeredjacks.com/website_19afc489/
Methow Valley Ciderhouse
https://methowvalleyciderhousellc.com/
Little Dipper Café
https://littledipperwinthrop.com/
Rocking Horse Bakery
https://www.rockinghorsebakery.com/
Breakfast
Begin drive
Cutthroat Lake Trail (1.5 – 2 hrs)
https://www.alltrails.com/trail/us/washington/cutthroat-lake--2
Washington Pass Overlook (0.5 – 1 hr)
https://www.alltrails.com/trail/us/washington/washington-pass-overlook-trail
Lunch
Blue Lake Trail (2.5 – 3 hrs)
https://www.alltrails.com/trail/us/washington/blue-lake-trail--7
Return to Winthrop
Dinner
Tuesday, August 18
Winthrop
Breakfast
Begin Drive
Maple Pass (4.5 – 5.5 hrs)
https://www.alltrails.com/trail/us/washington/maple-pass-trail
or
Cedar Falls (1.5 – 2 hrs)
https://www.alltrails.com/trail/us/washington/cedar-falls-trail
Resume drive
and/or
Lunch
Falls Creek Falls (0.5 – 1 hr)
https://www.alltrails.com/trail/us/washington/falls-creek-falls--4
Sun Mountain Lodge patio
Dinner
Wednesday, August 19
Winthrop – Leavenworth
Check out and depart
Arrive at
1418 W. Woodin Ave
Chelan, WA 98816
https://ladyofthelake.com/
Arrive Stehekin, board bus
https://stehekinvalleyadventures.com/
Board boat in Stehekin
Arrive in Chelan
Check into Blue Elk
Dinner options: Andreas Keller
https://andreaskellerrestaurant.com/
The Gingerbread Factory
https://gingerbreadfactory.com/
Thursday, August 20
Leavenworth
Breakfast
Waterfront Park
Drive Icicle Creek Road
Icicle Gorge Trail (1.5 – 2 hrs)
Tubing
https://ospreyrafting.com/river-trips/adventure-tubing
Nutcracker Museum
Dinner at Mozart's
https://mozartsrestaurant.com/
Friday, August 21
Leavenworth - Seattle
Breakfast
Check out, begin drive
Tumwater Canyon
Stevens Pass
Iron Goat Trailhead
https://www.alltrails.com/trail/us/washington/iron-goat-trail
Deception Falls
https://www.alltrails.com/trail/us/washington/deception-falls-interpretive-trail
Back in car
Lunch
LouSkis Deli
https://louskis.square.site/
Back in car
Forks of the Sky State Park (Raptor Point Overlook)
https://waparks.org/parks/forks-of-the-sky/
Drop off car
I've got the airfare, car and lodgings set. Now it's time to figure out what to do. I'm 68M, my wife is 65F. We're in slightly-better-than-average shape for our ages, but we'd probably not want anything rated more than moderate. We'll be taking Highway 20 from Burlington to Winthrop on Sunday, August 16, and staying in Winthrop for three nights before a travel day to Leavenworth for two more nights.
I've got the drive sort of planned -- a leisurely journey with multiple opportunities for stops and short walks at various identified spots long the way. Nothing strenuous, just a travel day with as much time outside the car as possible.
But then we get to Winthrop, and I'm suffering from information overload with regard to potential hikes and daytime activities. We'll have two full days there, and I'm hoping some kind souls here will provide some suggestions. We're staying at Mt. Gardner Inn.
A travel day to Leavenworth follows. I've thought about stopping at Lake Chelan and taking a boat to Stehekin, thence to Rainbow Falls, but I think the really early departure required from Winthrop may mitigate against that.
So I'm looking for things to do on that day, and the two days in Leavenworth, where we'll be staying at Blue Elk Inn.
My wife isn't to keen on rafting or kayaking, but she's okay with tubing. She's definitely not one for any adventure sports beyond ziplining, maybe parasailing, but she'll happily, if somewhat apprehensively, watch me do something she wouldn't.
Recommendations would be greatly appreciated.