I haven't done an organized century for awhile. However, my favorite of all that I've done is the Crater Lake Century -- I think I've done it 10 times.

It provides a bit of challenge without being epic, the scenery is top notch pretty much all the way with a nice mixture of agricultural land, woods, climbs, lake/alpine views, and descents. Number of participants is limited, so you never get the rolling zoo phenomenon. Here's a video I made of one of the trips. It does a reasonable job of conveying the ride.
One thing I might observe though is that there's a leg that goes out and back that are basically junk miles just to push the mileage over 100 -- they offer nothing that can't be found in the rest of the ride. So unless hitting that 100 number is important to you, I'd just chop off those 20 miles.

This would be a long trip for you, but I don't even know how many different ones I've done, and this one is a standout. Plus, early morning and nighttime temps can drop below freezing even in late August