Hello Chris
Welcome to the forum ... it's hard to know where to start with recommendations because there are so many.
You say you are going in the fall - just to advise, harvest time could be any time from mid-August through all of September or even early October depending how the season is and exactly where you are. This means roads full of trucks of grapes, lots of activity and not all wineries geared up to welcoming visitors as they will be too busy picking and processing grapes, however, it could also be lots of fun.
From Avignon, you could (and probably should) head off to the legendary hilltop village of Châteauneuf du Pape - not too far by bicycle. The very well-known domaines need advance appointments, but there are several good ones you can just visit anyway e.g. Château Mont-Redon, but even here you would need an appointment to get a tour (you can just turn up for a tasting 7 days a week). Website is
http://www.chateaumontredon.com. There are also tasting shops in the village.
You could also go to Tavel or Lirac or go southwest from Avignon towards Nîmes, and visit the more modest domaines of Costières du Nîmes. Try Mas Carlot in Bellegarde.
Both Arles and Aix are fine cities, but if it's wine you are after, I would head to Aix and perhaps Les Baux (here Le Riboto de Taven seems a pretty legendary restaurant -
http://www.riboto-de-taven.fr).
Hope this gives you a start for further research.