Connection in AMS to VCE - do we go thru customs in both countries? Travel pointers?

You will have Passport Control (Immigration) in AMS. Customs in Venice should be a non event in Venice unless you are importing goods. 55 minutes is cutting it very close, and you'll likely miss your connection if your flight is late. Since your flights are on the same ticket, the airline is responsible for getting you on the next available flight, but who knows how long until there is a flight with available seats? You can look at the Schiphol website, under Transfers for time needed between flights. I would not be comfortable at all with such a short connection time.

I'd suggest checking Flight Aware to research the on- time record of your proposed flight. Safe travels!

I have flown with Delta with connections in AMS that where around 60 minutes and I have always made my connection. On the other hand I don't really like it because if your flight is delayed 30min then you probably won't make the connection flight. One good thing about AMS is that all the concourses lead to one main area so there is no changing terminals, you will just have a long walk.

I would probably choose the flight through Atlanta because I like at least a 2 hour layover with flights overseas, and the flight from Atlanta to VCE is non-stop so the chances of a complication are very low, but that is just me.

It's a very long and confusingly signposted walk at AMS between flights, and sometimes there is quite the lineup to go through Passport Control.
If I were you, I would book the flights with longer connection times to ensure your trip goes smoothly.

Thank you all for your feedback! I think I will select the 1 stop / long layover flight!