I've got an authorised 200k DIY by GPS that goes from Inchbrook to Oxford station and back.
So the route has detours you wouldn't like. Tetbury, Malmesbury, Fairford, Bampton, Buckland, cross the A420 to Charney Bassett, then cross back to Longworth, Appleton, Cumnor, down Cumnor Hill to Botley and have fun along there.
The most exciting thing was being pointed at by a local in a cafe in Brampton, then he got hit by a car as he crossed the road without looking. (Voodoo dolls are very handy on DIY Audaxes)