Venice - 2 afternoons + 1 day

Venice is a unique and beautiful place. To me, the "highlight" of Venice is just exploring the unique neighborhoods, taking a boat ride on the Grand Canal, etc. There are certainly museums, palaces, etc. Pick up a guidebook like Rick's Italy book or browse through a few of the Venice tourist sites (easy to find online) and see what appeals to you - may not be what appeals to me.

At the risk of going over to the dark side, you might want to also take a look here:

https://www.tripadvisor.com.au/ShowForum-g187870-i57-Venice_Veneto.html

Why aren’t you flying on to Venice since you are at already at FCO? Book it as one ticket. You will have more time in Venice that way. We have done this, easy peasy.

Suki, sometimes it works best to get a direct flight to Rome and take the train to Venice instead of taking a connecting flight to Venice. That's how I did it the first time I visited Italy I wanted a direct flight, and Rome was my only practical choice. I preferred the train as my "connecting flight" to one in another European city with a layover, possibility of a missed connection, etc.

We attempted to get a direct flight into Venice, but all of the connections, including those at FCO were really tight. My parents are in their 70s and the idea of sprinting across an airport to catch a connecting flight or getting hung up in the passport line at FCO and missing our connection just didn't appeal to them. When I suggested the train, both of them relaxed, so that is what we are doing.