I've done the "Tour de Noto" the past two years with some friends. It is a fully supported ride and in the past has been held over the 3-day holiday weekend that is the 3rd weekend in September. Very pleasant scenery once you get past Kanazawa and onto the Noto Peninsula. Well organized. Very Japanese. Not much serious climbing -- a few hills each day, and rollers along the coastline, but much less elevation gain than if you ride a similar distance somewhere near Tokyo or, say, through Izu. The weather in September on Noto can still be very hot (last year), and it can rain (morning of second day in 2006). It would be even better if they moved it back a week or two in the hope of getting cooler, drier weather.
The last two years the fee was 30,000 yen for the ride, including lunch, drinks, snacks, etc. plus around 8,000 yen a night for accommodations (minshuku) with dinner/breakfast, plus you will need to get there and back by train, plane or automobile -- last year two friends and I did the 6-7 hour drive from Tokyo, starting at 8PM. If you don't speak/read Japanese, you will need someone who can communicate in Japanese in your group to make the reservations and coordinate otherwise -- there were probably fewer than 20 non-Japanese among the 600 riders who did the full 3-days last year.
I have a schedule conflict and will not go this year, but may again sometime in the future.