Provence

St. Remy has a fleet of four regular taxis in service. If a couple of people in your group are willing to drive, renting two cars would be the most flexible option; look at Auto Europe for a price quote. www.provence-reservation.com looks like a place where you could arrange a private van and driver, in addition to their set tour options.

You are in such a lovely town and using it as a base to tour Provence and Luberon regions is wonderful. But I do suggest a car or van. Nimes (Roman Amphitheater), Arles, Pont Du Gard, Aix en Provence ( a beautiful city with a lovely central promenade Cours Mirabeau), Avignon (Pope's Palace) and lots of tiny villages (even smaller than St. Remy) to stop and savor.

My daughter and I had a wonderful day trip with Provence Panorama in May 2013. We did the Villages Monuments Chocolate Wine trip - I may not have the name quite right. Our driver took us to 8 or 9 different sights over the course of our 9 hours with her. St Remy, the Roman arch and townsite at Glanum, Les Baux, Pont du Gard, a couple of roman sights in Orange, etc. Based on our experience I warmly recommend Provence Panorama for a full or half day trip in the region. They have a number of different itineraries. We did not have a car on that trip and were able to see quite a lot on our own using trains to get around but could not have gotten to all the sights on our tour day without an expert driver.

Have a great trip!

Here are some things we (large group of adults) did when we rented a place together for a week in St. Remy.

Boulliabasse lunch in Marseilles.

Streets of Aix, plus visit to Cezanne studio.

Walk in Luberon Hills (Foret des Cedres), with dinner in Lacoste (hill town).

Sites in the Sorge valley, including Fontaine de Vaucluse and its Resistance Museum.

Magnificent Pont du Garde in Uzes, near Nimes.

Les Baux

Roman antiquities: Arles arene and temple, Orange theater, St Remy Glanum.

Other things too but these were highlights.

We could not have seen nearly as much without renting a car. I know this is not your plan but I strongly recommend it. With such a large group, surley someone can drive. Maybe even 2 cars.

We attended a 'bull game' in the area. There are several posts about bull games on this Rick Steves forum, including this one:
https://community.ricksteves.com/travel-forum/france/french-style-bullfighting-april-and-may-near-arles

Also, we really loved the Carrieres de Lumieres, which is very close to St Remy:
http://www.tripadvisor.com/Attraction_Review-g1819081-d2651179-Reviews-Carrieres_de_Lumieres-Les_Baux_de_Provence_Bouches_du_Rhone_Provence.html
It's a fresh way to look at art. Provides a little relief from looking at old piles of rocks : )

Definitely attend a market. Here is a website showing when they're scheduled:
http://www.avignon-et-provence.com/market-provence/market-provence.htm#.VKVnQaZChbw

The driving in this area is easy. I agree with everyone else that a car is highly desirable.

You haven't given any details about the make-up of your group, but I have some advice based on our experiences with large group trips. Traveling with other people can produce strains that you don't anticipate, one being decisions about where to go each day. Having 2 or 3 cars (with 10 people, I recommend 3) will not only give you flexibility for time and destinations, it will allow people to choose differently if they don't want to do as the others do. The three times we've been part of a large group, the format was roughly this. Each evening we assembled and discussed the next day's agendas. We then sorted ourselves into car groups, taking into account those who preferred early vs late starts, activity levels, etc. Some days some people just opted for relaxing at the villa. Car rentals in France are surprisingly inexpensive.
If you haven't already worked out your plan for food preparation, here's what we did. We kicked in 100 euros/pp to start. Each night one couple prepared dinner for everyone. Anyone who purchased food or drink for the group reimbursed themselves from the kitty. We ate one gala meal out during the week. Any money left was shared out at the end. By the third trip, one of those "strains" had arisen, which necessitated a modification. Some were big drinkers; and others, teetotalers. The latter resented subsidising the alcohol consumption of the former. We established a separate kitty for alcohol, allowing those who drank little or none not to contribute.
These arrangements worked very well, and a good time was had by all.

les baux is a must and seriously think about buying some artwork there. and near to les baux is cathedral des images, the interiour of a marble quarry featuring beautiful classical music and impressionist artwork. nick from santa cruz