Im there 
I know quite a few good roads, unfortunately they are only around 45 minutes long each and I havent really worked out nice link roads from one route to another. So if you have a route in mind ket I could maybe suggest diversions along it.
A4074 Oxford to Reading is good, my fave, although can be busy at times
B4494 Wantage to Newbury is good too, but can be very windy, no cops or traffic though.
B4057 Wantage to Ashbury is pretty cool, but roads can be mucky and tight.
Ill ask a friend about a long route, I usually just follow him.