Are you going to ride the whole way? Or just the "best" stretches?

I really don't know enough about your fitness to take even a wild guess at how long it will take you. Especially day after day. Or are you going to take rest stops?

If it's a one way trip from Cle Elum to Leavenworth, take Old Blewett Road over Sauk Pass and avoid Blewett Pass. It'll be steeper but you probably won't see a single car the whole time. Arguably more scenic, they're both nice enough.

Are you going into Leavenworth? It's about 5 miles out of your way, 5 more to get back to your route. Personally I think it's very worth it. If you can get time for a side trip up Icicle Canyon it's very worth it. Take an extra day here if you can.

I don't have much to say about the trip from Wenatchee north, although I can recommend a good route from L'worth to Wenatchee if you like.

Then Winthrop is a wonderful little outdoorsy tourist town, and the ride from here to Sedro Wooley is absolutely gorgeous. From Mazama to Diablo Lake you will find nothing: no stores, no water fountains, nothing. It's 50 to 60 miles, and hot and sunny. I recommend a water filter for the creeks.

You should have an easy time researching mileage and elevation gain (google maps bike directions), let me know if you want specific route recommendations or photos for any of this and I'll do my best.