Blois is beautiful,
Great, friendly airfield with a lot going on and a Michelin starred cafe. The city is stunning, on the Rhone Valley so a great wine destination and outside the palace is the House of Magic. My last visit I spent a couple of hours watching the dragons:
St Denis gets my vote as well, and I was surprised by Lyons, We were nightstopping at Lyon Bron, on the taxi ride to the hotel we passed through the usual French industrial area, and found ourselves in a superb hotel in the centre of the city (Ops aren't normally that kind!) The old town is gorgeous and any of the restaurants in it are worth a visit, there is a lot to see and do there.
Slightly more adventurous, but again beautiful is Grenoble Ver Sud, another Michelin starred cafe on the airfield and a short taxi ride to one of my favourite French cities where I reckon I'd need a large chunk of a lifetime to see everything.
If you're a foodie get a copy of the Gault-Millau from Amazon. While the Michelin is good the Gault-Millau is also a fascinating read. They cover a lot of the world, but not the UK (they reckon there's no such thing as fine food in Britain)
SND