Italy to France Train Travel

It will take at least 10-1/2 hours to get from Venice to Marseille by train. I'd see whether a flight is available. I use skyscanner.com to look up schedules for intra-European flights, then I go to the airline's website to make the purchase. Check carefully into size and weight limits for checked and cabin baggage.

Trenitalia website for buying Venice-Marseille tickets.

SNCF website for booking Marseille-Chartres and Chartres-Paris tickets.

Marseille is a fairly unusual destination in this situation.

Wow, that's a tall order.
Its 11 hours from Venice to Marseille, with a train change in Milan.
Trenitalia was a group desk you can email. ufficiogruppi@trenitalia.it
You could also contact their travel agency in the US, Italiarail. There will be some commission involved, but could be worth it for a big group.
https://www.italiarail.com/

For France, SNCF Group offers at
https://www.sncf.com/en/passenger-offer/travel-for-everyone/group-travel/travel-with-others.
Going from Marseille to Chartres, you'll have to go to Paris first and change stations. Might be easier for you to just go to Paris and do Chartres as a day trip.

Milan-Marseille is a day train. That is the one you would use if leaving Venice on the 7:18 am Frecciarosso, then 1 hour 25 minutes to change to the Thello train to Marseille.

Thankyou I have looked at this alot. The plane involves catching a bus to go to the airport, whereas the train station is right there in Venice. Thinking the less transfers the better with this group. The plane then goes to Amsterdam and then Marseile getting in later then the train does and with our rentals at the train station, again less transfers. So that is why we are preferring the train.
I like the Milan transfer as it gives us 1 hr 25-30 minutes to get oriented and know where we catch the leg to Marseille.

The trip to Chartres is yes thru Paris, but it keeps us out of the city for at least another nite, waking up in Chartres to see the Cathedral and Labyrinth. Then onto Paris to Gare du Nord with a transfer to Etienne Marcel metro to walk 2 minutes to our loft. 4 days later to catch the train to CDG airport.
Is it worth while to purchase a train pass if thats even possible or just purchase tickets as we need them. Not familiar with how the trains run in France...if its a free for all once you get on to find a seat. With small children I would like to be very organized to not leave anything to chance. Have been working on the logistics of our family trip for a year. Have all accomodations, flights, rentals....now working on regional travel. Any suggestions for purchasing train travel?

The trains from Venice to Marseille will have seat reservations for both legs. The train from Marseille to Paris Gare de Lyon will be a high speed TGV with all reserved seats. But then you will have to get your crew over to Gare Montparnasse to get a train to Chartres. Its a local train, so I don't know about seat reservations. That will involve some logistics, by bus or a fleet of taxis. When you come back from Chartres, you will again arrive at Gare Montparnasse, and have to get to Etienne Marcel, by the No 4 Metro, or again, a fleet of taxis.

A rail pass would be throwing away money. Contact the group desk at Trenitalia and SNCF, you get discounts and seat reservations for advance purchase tickets. Good Luck.

There is no through train to Chartres, you must change to Montparnasse station in Paris.

Volotea flies from Venice to Marseille. Not daily I tjink, but I'd consider reshuffling the schedule if needed in order to fly! The train will be long, and involve at least 1 connection but more probably 2.