"We much prefer the Gorges du Tarn & caves (plural), over the Ardeche Gorge & cave."

The suggestion of the Ardeche was for the kids to get into the water based activities Stu. Driving in the Gorge isn't required, just access to the water.

It isn't about one being better than the other. It is about there being more than one place that may be of interest to the OP and the kids.

So no, it isn't what YOU prefer that matters. Tell me how driving in the gorge is going to be of more interest to the kids?

If you believe that the Tarn Gorge would be preferable for kids than explain why. Driving in it certainly isn't a reason to suggest one over the other. I suggested the Ardeche because I believe the swimming and canoeing etc. that is easily available would appeal to them and indicated that with the picture I linked. If the Tarn has more to offer kids then that would be worth letting the OP know about. Your personal preference is irrelevant.

I feel exactly as nononora does about Monaco.

We were in the Luberon the last week of June last year and were a bit early for the lavender, not at the tail end.

The Luberon is a really nice place to visit. The mountains are beautiful in both summer and winter. I found charming cottages to stay during our vacation. We found beautiful cities like Manosque. In south of France there are many regions that deserve to stay several days. You can take a look at http://www.lesclesdumidi.com to find various interesting places.