Flights to Italy

My experience with customs/passport control in CDG is that it is very unpredictable. You might very comfortably make a 2 hour connection or you might easily miss it....that's even if your flight into CDG is on time. If your flight is delayed even half an hour, then you'd likely be speaking French much longer than you'd hoped. Those extra two hours will buy you not only a much better chance of making your connection, but also might alleviate a great deal of stress en route. I would clearly take the longer connection time... but I've missed connections because of slightly delayed flights and/or long passport/immigration lines before (here's looking at you, JFK and Dulles), and thus tend to fly conservatively, when connection times are involved.

The minimum connection time for that connection is 60 minutes, so 2 hours gives you double that.

You don't have to collect your bags in Paris, they just stamp your passport and you're off.

CDG is a huge airport, and often busy and chaotic. Also between touch down and actually getting to the gate it's often a long way, first because of a long taxiing, but often also because the gate may be still temporarily occupied by a departing flight.

Having said that, having gone through CDG multiple times (and missing my flight to Florence various times), I would encourage to take a chance and go with the shorter layover.

If everything goes according to plans, you get to VCE 2 hours earlier than with the other option. And if things go wrong, no big deal. Go to the AirFrance transfer desk. Since you are on a code share flight (Delta and AirFrance are partners in crime with SkyTeam), AirFrance will rebook you on the next flight to VCE, which is operated by AF (probably the same you are considering with the longer layover option).

So you've got nothing to lose, except for a drink, because whenever I missed my next flight to Italy in Paris, AirFrance, after rebooking me on a later flight, always gave me a coupon for a free drink and some food to go with it. Not sure they are still that generous nowadays, but who knows.

You will go through passport control in Paris, and customs in Venice. Passport control lines can be short or lengthy - no way to predict. Customs is just a matter of walking through the Green Channel - Nothing To Declare lane.

Since you're all on one ticket, you will be "protected" as Roberto describes - they will put you on a later flight if your incoming flight is delayed and you miss the first one. Therefore, I'd go for the two hour layover.

My personal CDG connection story: I had 3 hours between flights there, but my flight leaving JFK was delayed by a storm, so I had only about an hour to get from terminal 2E to 2F. I was running and stressed, but at the security checkpoint, the screener told me not to worry. She said I had time to relax, get a coffee, and meet a girl. Yes, she actually said that. Now, I'd rather have met a boy, and there was no actual romance on that sojourn through the airport, but it was comforting to know that it actually is possible to make a tight connection at CDG (I'd read the same horror stories everyone else has).