These are some valid concerns we need to hash out.
The first day from Tacoma to Medical Lake is about 350 miles and good roads. Even with a stop for lunch you guys should be able to do it in 6-7 hours.
The second day (Day 1 from Medical Lake) is the killer. Just straight riding is about 10 hours. With stops for food, gas, pictures, stretching will run it into at least 12 hours I think. That's a long day for anyone.

Here is an amended 1st day from Medical lake. This would get the Spiral Hiway and Rattlesnake Pass on that day. It would be an overnight in LaGrande.
Day 2 Would be Snake Canyon Dam and then head west with an overnight in Umatilla or somewhere close by.
Day 3 would get you back to Tacoma via superslab along the Columbia River.
These rides would give plenty of time for sightseeing along the way, plenty of time for other stops and possible rerouting into side roads if it looks good.
This is just an idea I have thrown out so we can get maximum participation. There is still plenty of time to play with days and routes. I am still open to whatever the consensus is.
bob
bob