i and my family (wife and 2 daughters 15 & 14 years old) arrive at Paris on Thursday 22 Aug. till Thursday 29 Aug. ...should I buy Navigo to me and my wife then t++ tickets to my daughters on Friday then Jeunes cards on weekend then Navigo for all of us on the following week. Is there any other way to save money?
If you arrive/depart using CDG airport, then buy Navigo week pass for everyone on Thursday Aug 22 and renew it on Sunday for use until following Thursday Aug 29. It will be the cheapest least hassle option.
If you're not arriving by CDG Airport, then yes Ticket Jeunes for the kids are a good idea, followed by Navigo week passes for them.