Carte Advantage Senior/Adult

Each is individual, so 98€ or $106, for two.
Many of your trains are local trips and the card doesn't work on the locals. Others, begin or end outside France, so it affects the usage. So, in your case, I doubt you'd recover the $106.

I agree with Bets: the cards are useless in your case! Even if you actually can share a card between two people travelling together (it's a fairly recent development, you need to pick the "Accompagnant Carte" fare for the passenger who does not have the card).

By the way, what are your plans for a day trip in Avignon? Avignon is interesting to visit of course, but I'd rather "do" Nîmes or Arles which I feel are more packed with places of interest, personally.

Thanks for the feedback. I was beginning to think it might not be worth investing in the card. Appreciate the prompt response.

Avignon for the Palais du Pope and just to see the town. I am open to suggestions, though.

See Avignon!

A friend and I spent 4 nights in Avignon last November and really enjoyed our time there.
We booked a walking tour of the town for our first morning with Nina Seffusatti, a Rick Steves tour guide who lives in Avignon and gives tours when she is available at home. We found her to be delightful and knowledgeable and that really put the town in perspective for us. I can recommend her without hesitation.

Thanks for the tip about Avignon. I worked it into my plans.