Lyon to Arles in a car - suggested stops?

If you are pressed on time, if you can, take the TGV to Avignon TGV and rent your car there. You'll save a boring, traffic-prone 2.5-hour drive on the A7 motorway. Otherwise, just drive straight through.

If not short on time, then there are indeed a few good stops along the way, including:

• Vienne/St Romain en Gal with some very interesting Roman ruins, a good appetizer for the ones in the south.
• Palais idéal du Facteur Cheval. Google it, it is...hard to explain.
• Tain l'Hermitage, a cute riverside town with an interesting chocolate museum (Valrhona)
• Orange, for the theater

None of this warrants an overnight stay, but if you have the time, then Tain l'Hermitage or Tournon across the river would be pleasant.

ecarger,
Just in case you missed it, every recommendation I have read on this forum is to not rent a car in one country and drop it off in another. The extra charges are very, very steep, if even allowed with your rental company. Also, if you have more than four people, you may need to rent two cars for the drive. With luggage, you will be squeezed. We were seven and had two cars for our multigenerational trip to France this year for our 52nd wedding anniversary and my husband's 80th. It was a success...youngest person was nine, oldest two were 79 and 80. We all arrived at different times for different lengths of stays, but had 9 days when we were all together, at a gite we rented in the Dordogne region. Be sure to check car sizes and luggage space for whatever car you rent.
Have a great family trip! Make the most of this time together.

If you are not going that far into Spain, consider ending your trip in France close to the border, perhaps, Marseilles.

I'm sure Balso's recommendations are very good. The only one I've seen is the theater at Orange, which is well worth a stop, even with traffic in the city. You can go in at the street level, but it might be worth going up a few rows for better views.

Another worthwhile stop would be the Pont du Gard, a few miles west of the A9 between Orange and Nimes. One of the most impressive Roman achievements we still have, it's an easy walk from the parking lot to the aqueduct, with an excellent museum along the way if time allows.

Nimes itself has a very good amphitheater, the Maison Carree temple, and Roman museum. According to Google Maps, the fastest route from Lyon to Arles takes you past Nimes.

Optimal driving time from Lyon to Arles is about three hours, but it will take longer because of traffic and of course any stopovers. If you want to break the trip into two days, there are plenty of places to spend the night along the way.

You will pay a big dropoff fee if you get the car in France and return it in Spain. You might be able to reduce it by returning the car in France near the Spanish border, taking a train or bus across, then getting another one in Spain. But the saving might not be worth the inconvenience and cost of that alternative.

Thank you everyone, these suggestions are really helpful. We are not dropping the car in Spain, we are making a loop all the way around Spain as the longer leg of our trip and then some of our group are continuing back up to the French alps and others flying out of Barcelona. I lived in Spain so I have that part covered I just wasn’t sure about the Provence part. Thanks much for the suggestions, I will definitely put them to use!