I will have the morning of May 9th in Avignon before departing by TGV for Tours around 13:00. Does anyone know an interesting tour guide that could give us a quick look at Avignon?

All you really need is the Michelin Green Guide to Provence.

The old walled city is very walkable on your own. Start at the city tourist office, 41 cours Jean Jaures, the main street which runs from the old train station to the Palace of Popes. It has printed material to guide you around the ramparts, and the staff typically have been very helpful. Its website http://www.avignon-tourisme.com/home-1-2.html overflows with suggestions to check out in advance and it mentions guided tours.
Remember that the TGV station is not downtown; you must take a shuttle to the outskirts for the fast trains.

Thanks, it sounds pretty straight forward. I usually tour on my on;but, occasionaly I have enjoyed the input of a tour guide. We did that in Siena, Athens, and Rome.

We highly recommend Marlene Boyer who runs a small tour company www.experience-provence.eu
We so enjoyed our time with her and the knowledge that she shared. The best part of our trip was the time we spent with her. She's a real native of the area, if I remember well, born in Avignon. She gave us a tour of the town and drove us to Pont de Gard on our last day, right before taking us to the train station.
We keep reminiscing about these fantastic days in provence and how thoroughly we enjoyed the atmosphere and the food.
Marlene litteraly was the highlight of our trip.