+1 Know that stretch pretty good. 203 and 9 are a rated 5 on a 10 in my book. Just a pretty overall mellow ride. And high ridge rd has too many Sunday drivers. I-90 has too many cops; always want to travel through time on it. Black diamond area is good. Same with hwy 410. IMO. Good little run you have planed there.high bridge road is a really good stretch. gravel can be dangerous, though. ben howard road (just before you cross the skykomish river into monroe) is a nice little section, too. i live downtown and do a circuit of I-90 bridge to mercer island, do a lap around mercer way, head out to fall city or snoqualmie, north on 203 to ben howard, follow that to highway 2, back through monroe to the old monroe-snohomish highway into snohomish. follow the river (south bank) back towards everett, left at the stop sign towards seattle hill road, through the valley towards highway 9, cross 9 - take a right to spaghetinni road, to high bridge, to redmond, to 520 and home again. ~150 miles of decent roads.
also, highway 2 is great on weekdays. take 97 south after leavenworth to hook up with I-90 again. btw as far as superslabs go, I-90 is the best i've ever ridden.