SNCF discount cards are half price for one week

Thank you for this post!

If I am understanding the site correctly, the Jeuene discount card for 12-27 years old includes train tickets during weekdays - while the Adult card for 27-59 only includes weekends (but provides a discount for a companion)? Is that accurate?

I am traveling next July with my two adult children - one who is 26 now (27 by July) and one who is 21 now (22 by July) - and we will be traveling via train from Brussels to Paris, Paris to Bordeaux, Bordeaux to Paris, Paris to Saint Germain, Saint Germain to CDG airport, and all around Paris - both during weekdays and weekends.

I'm trying to figure out the best option to have the best overall discounts for weekday and weekend travel:
* 2 adult and 1 Jeuene cards
* 1 adult (with Companion) and 1 Jeuene cards
* 1 adult and 2 Jeune cards

Thank you very much for your recommendation!

I know the details only for my own card, the senior card.

However, I don't know how many trips you could use a card. Saint Germain en Laye is the RER, suburban transit, not the train. Right now Brussels is on the Thalys train, not SNCF, but I believe that is changing. Your only trip for which a card would give you a discount is Bordeaux. You need to check the prices to see if you'd save enough to justify buying the cards.

The card would only apply for the Paris-Bordeaux round trip, and yes you would only need two (adult card + accompanying passenger, + youth card for the other passenger).

If your dates are set in stone, you can set a reminder to buy tickets as soon as sales open, probably some time around early March. SNCF Connect website lets you do so. That way, you will get the cheapest tickets.
At popular travel times, the cheapest tickets realistically cost 90€ round trip if bought well on advance. The card guarantees a 30% discount on all fares, so you would save about 27€ per ticket.

27€x3 in minimum savings vs 25€x2 for the cards: the math is in favor of getting the cards!

And if somehow there are even cheaper tickets, you still won't have overpaid.
I would get the cards.

It doesn't look like I can use this discount on tickets I've already purchased for a day trip from Strasbourg to Paris and back (darn, because they were rather expensive), but it will probably still save me money on regional trains during my trip, so thank you!

Most tickets are refundable up to a week before. After that there's a 19€ charge.
Would it be possible for you to refund your tickets and buy new ones with the card?