accessible castle hotel in France
 

We will be travelling from paris to cinque Terre (via cote d'azur, most likely). We are looking for a hotel or b&b that is also a castle to stay at that is - if not on the way - not too far out of the way. We can rent a car but don't want to drive really far or really windy roads, if possible. Along the lines of chateau de trigance - old castle as opposed to 18th century ornate type.
does such a place exist?

You have a world of options on such a journey. How much time has you set aside? And how is your budget?

You can try the Château de Castel Novel, which dates from the 13th century, or the Château de Codignat, which is from the 15th century. The Château de la Caze is also from the 15th century. The Château de Bagnols, outside of Lyon, is from the 13th century. The Château de Rochegude is from the 12th century. In Provence you'll find the Château de Trigance from the 11th century, as is the Château de la Chèvre d’Or.

We are planning 2 nights at 200 Euros or less/night. I will look those up, thanks!

Have you checked out the Relais & Châteaux site?

http://www.relaischateaux.com/en/

For châteaux accommodations try these sites:

http://www.bienvenueauchateau.com/
http://www.relaischateaux.com/
http://www.symbolesdefrance.com/
http://www.chateauxdemeures.fr/
http://www.chateauxhotels.com/
http://www.au-chateau.com/
http://www.tablethotels.com/

The majority of châteaux are only going to be accessible with a rental car.