The Barvarian town of Leavenworth is one of the highiights and depending on the time of the year, you can see salmon runs west of Leavenworth.
As you go further east, you will hit rolling hills of orchids in Wenatchee and Chelan area, the east dry side of Cascade, It has a little Napa Valley feel, except these are apples, cherries (in early summer), and many other farm products.
It's an outdoor lovers paradise in the Leavenworth area.
The link below gives you details of the drive.
http://www.weather.com/outlook/driving/scenicdrives/?sd=wastevenspass.jsp¶m1=USWA0282¶m2=USWA0227