Drive from Bayeux to Arles...

It is ridiculous to call that a 9-hour drive, unless perhaps you drive all night when traffic is light, and do not need to stop for food enroute.

Bourges and its cathedral have a great reputation, and it is a stop on some of the Rick Steves tours.

It does not sounds as though you are especially interested in Bourges, but just need a place to break your journey on your way to the place you really do want to be.

In such a situation I would not waste a day on the road but would take the train and arrive in Arles a day earlier. (Or spend the extra day in Normandy or elsewhere).

If you take an early train you can be in Avignon by a little after noon, where you can pick up a second auto rental at the station. Arles is about 20 minutes away.

I would take the train, too.
If you check fares on the SNCF website, you can find good deals, especially if travelling outside of rush hour, etc

Gas, parking and toll roads are expensive.
If you decide to hire a car when you get to Arles, I'd reserve one ahead of time and pick it up at the train station.

Do you realise that driving the length and half the width of the country will cost you nearly €100 in tolls alone? And that fuel will cost nearly half that again? You can't speed (130 kph when its not raining and only 110 kph when it is) because the hundreds of speed cameras hidden along the route will have you for lunch.

I'd go a little bit out of the way and either go to Dijon or Lyon - the food is better.
You could shave off a little bit of time if you go to Dijon.

Could you post your full trip itinerary? There may be some room for a proper visit to Burgundy or our input may be different once we see the full context.

Our plans include to spend 5 nights in Brussels, train to Normandy area for 5 nights, drive and spend 5 nights in Arles area, finally fly back to Paris and then home. We enjoy driving and seeing the countryside.

So is this a 15-night trip or an 18 night-trip?
Arles is the outlier and will require at least 3 days' driving for the round trip. Dijon is a half-way point or a little north in Auxerre or Vezeley.

I'd drive to CDG, turn in the car, fly to Marseille and rent another car. Then I'd fly back to Paris from Marseille. That's a lot of autoroute humdrum. You won't see much of the countryside or interesting sites unless you get off the autoroute and then the trip could take days.

The only reason I don't say to take the train is that you already are paying for the car and once in Paris you'd have to change train stations, so flying from CDG could be easier because the Bayeux--CDG drive is so easy.