Thanks to helpful fodorites, I've utilized www.sncf.com to find a TGV from Paris to Avignon on Monday morning, 9/26/05.

The website says that "reservations are required." What, exactly, does this mean? Must my group of four adults purchase tickets in advance via the website? Or can we purchase that morning at the station? Is there a fear of a sell-out?

Thanks again.

You cannot guaranteeably board TGVs without reservations as they may well be full, especially on this route. If you do board with tickets but without reservations, if empty seats remain, the conductor will charge you a penalty fare plus the reservation fee - about $15 penalty i incurred once doing this when i didn't have time to wait in a long line at a ticket window to get a reservation. If your train is full there are plenty others - about hourly on this line and in worst case scenario take a TGV to Lyon (twice hourly service) and then take local non-TGV train to Avignon (can always board these local trains without reservations - though seats may be full).
If the train is full you can ask for a 'Sur-Reservation' ticket where you can board the train and then the conductor will find you a no-show seat or put you in a folding seat in the vestibules, etc. There are a limited number of sur-reservation tickets sold on each train i believe.

Did you check for PREM fares on that route? It's very late to be doing so, but they nearly always have them on that line, and that would both save you scads of money and make the reservation issue moot, since you'd print your ticket from your computer and automatically have a reserved seat.

It means exactly that -- for all TGVs, you have to have a reservation. I don't think it is possible to buy a ticket without one. Interesting info from Bob on the sur reservation ticket thing, never heard of that.

However, you can do it at any time up to departure, so sure, you can do it that morning at the station. There is no requirement you do it by the website.

I wouldn't know the likelihood of it being sold out, I would think not likely, if you are willing to take first class, especially.

Is there some reason why you don't want to purchase the tickets in advance with the reservation? It sounds like you know the exact train you want. If you are afraid you'll miss it due to a plane or something, I can understand why you might not.

Thanks for all the info.

I'm traveling with a group of friends, and, if we enjoy the Paris nightlife until the wee hours, we may want to leave at 11:30 as opposed to 9:30, so flexibility is an added bonus.

No PREM fares are available for Monday, unfortunately.