Actually, after suggesting the 8-12th, that won't work for me now either. Later is better for me too. Anytime after Aug 20th is best for me.
As for North Cal, I have been there most years in the past 6 or so years. Some absolutely great roads. On this years trip we did 4 nights in Chico and rode the stuff East and South. Hwy 36 is great as well, but some even better stuff just a little North.
The only challenge is that you need a full day+, each way, to get from Ellensburg to anywhere nice, so it can make the trip a little long. Especially, if you want to do some fun roads on the way down. How much time has everyone got? Our trips to North Cal have usually been 9 days riding (8 nights). Day 2 this year went from Wenatchee to LaPine, Oregon. Nice day, but still 700+ kms, and then another 650 kms to Chico the next day.
So...two things to get organized:
1. How many days has everyone got?
2. What date to leave and return?
Then we can plan a route.