I spent two weeks in Tuscany and Umbria last May, had an excellent time. Very scenic, very cycle-friendly (at least the parts I was in), lots of history and culture in Florence, which is about as big a city as I care to visit. I'm hoping that my next trip over will be longer and I will try to take in Sicily, Sardinia and Corsica, as well as the part of Tuscany north of Florence.
In France, the Pyrenees are beautiful, and not as touristy as the Alps. That whole region has a very remote feeling to it.
The Scottish Highlands are pretty, especially the west coast, but the weather can be iffy. The Hebrides Islands are a great place to island hop with a bicycle, take the ferries from island to island.
Wales is very scenic, the Lon Las Cymru (Welsh National Cycle Route) is an excellent ride.