Nice and Provence in May with kids

Avignon has a carousel for Xmas but I'm not sure if it's there in the summer.

With the car, you'll find that there are plenty of small pull-offs to the Rhone river and its tributaries
where people are doing a little casual family splashing and sunning.

The kids might like the bull-jumping at the amphitheaters in Arles etc. -- no violence, just a lot of limber young men grabbing rings from off the bulls and then getting out of the way.

Follow Rick's advice about how to time your car parking so that you can go to market days but still not have the car be blocked in.

I think you will find most Roman ruins in or near Nimes, Arles, St Remy, Orange, Narbonne, Vienne, Lyon.

There is not much Roman to see near Aix-en-Provence but that is where Ceasars uncle Marius defeated the Teutonic invaders who had wiped out other Roman armies. They say the name Marius is still popular there.

More generally I like Avignon, Aix, and Nimes to stay a while.

I would suggest adding Antibes to your mix you.

In Nice, there is a carousel near Jardin Albert 1ere (near the Promenade des Anglais) and one on Place Garibaldi. The Promenade du Paillon has extensive playground area. There is the Petit Train de Nice which isn't track bound but a small touristic wheeled train that hits all the major sites, including climbing castle hill. There is one in Menton and Cassis as well from the same company. There is a steam engine train along part of the Train des Pignes (Chemin de Fer de Provence), but the journey may be too long as you must take a train first to Puget Theniere. Close to the airport and reachable by Tram Line 2 is Parc Phoenix (gardens, playground, aviary/small mammal zoo). There is also a very good aquarium in Monaco (near the old town/Palace).

If you go to Eze and Peillon, directly on the windy street connecting the two is La Turbie, with La Trophee des Alpes (Roman monument of Augustus, celebrating conquering the Alps). A bit of history and great views down on Monaco.

Between Arles and Les Baux is St. Remy and Glanum. Glanum is a pretty large and laid out site of Roman ruins. With Arles, Nimes, and Orange you may get some Roman theatre fatigue, btw, although each has their highllghts. If you haven't been, you should go into the Luberon Valley beyond Gordes and see Rousillon. The short walk into the red clay area may be interesting to the older kids. That's a lot of territory, from Vaison la Romaine to Cassis, to cover in western Provence and the Southern Rhone valley.