It was rather a fluke that we booked the tour. My wife rec'd an email from a Napa Valley winery promoting a wine tasting tour in the Provence region of France, which was seven days cruising the Rhone on a river boat. The selling point to us at the time was that someone in the wine industry, from the USA, was going to be on the trip - and in our casual reading of the literature we assumed they would be taking us to places and doing more than what was on the 'basic' tour. So we booked it. And of course, if you're spending the money to fly across the pond and you're already THERE, you might as well add a few days.
The boat holds around 150 passengers, and around half of us were part of the winery group, but the reality was that everyone on the boat had access to the same tours, except for a gourmet dinner with the winery owner in a special room and a few other minor attractions. The end result being that the tour would have been just as good had we booked it on our own but yes, it was a tour within a tour.
And the five days in Barcelona and three in Paris were with the same group as well, which actually proved to be a plus. We've been to Paris before on our own, but the tour took us a little out of our element and we ended up doing a few things we might not have done on our own.
I'm not quite sure if you have a trip already planned to the south of France which does NOT include Arles and you're thinking of including this in a future trip, or if this is all part of your planned trip. And if you've not been to Barcelona, let me know and I'll do my best to convince you that if you're this close it is a MUST see. One of the most incredible cities I've been to.