I think Devils Gulch-Mission Ridge out of Cashmere might be the best. Its long, its hard, yet its not too technical. It has everything you could want in a Washington ride. You climb Devils Gulch and you are in the woods crossing streams. You hit Mission Ridge and youre exposed with great views. Not sure of the total distance, but I think if you run the complete "figure eight" its about 23 miles plus about 5000 feet of climbing. If you finish this ride ealy enough you could go to Leavenworth and hit Freund canyon for another 8.5 miles and 1500 feet or so of climbing. Both of these rides are on the east slope of the Cascades about 100 miles or so from Seattle. If you check the forum here the best rides has been kicked around a bit.