You'll have a great day in Rouen - that's where we go for our French trip! The Musee Jeanne d'Arc is quite good for a half hour visit - if you go on their website, there's a worksheet that they can fill in on their way around. I adapted it for my lot and they get on well with it. It's 2 euros ( I think) entrance fee. If you're letting them have free time, then Rouen town centre is virtually all pedestrianised and easy. We give our kids an hour to shop in groups of 3. Just up from the museum is the 'gros horloge' - a cool clock that is iconic in Rouen - you can go up to see the workings of the clock for 4 euros each. The cathedral's really impressive - that's free. I was surprised at how interested our lot were. We have a guided walking tour (booked through the tourist office) - it was 95 euros for 40 of us last month, so not bad at all. The lady we had was great, and was a fluent English speaker. Have fun!