Zurich to Cinque Terre? Crazy or doable...

TOTALLY not worth it!!! I loved the CT have been there three times, but it is not worth the incredible effort you would be putting into it. Spend your extra time in Switzerland.

Are you leaving too much to chance? In a word, yes. There are plenty of wonderful things to see and do in Switzerland, so make the most of them!

. Obviously, the challenge is getting there and back for a 2pm flight
on the Sept 8. ... Leave on Sept 8 from Zurich and fly into Milan (~1
hour) and then train to Monterosso. Return from Monterosso on a train
leaving at 5:15am on Sept 11 and gets into MXP (airport) at ~9:45am.
We then catch an 1110am flight to Zurich which gets in at 1210pm. We
then leave for the a flight back to the US at 2pm.

This is plain crazy. What happens if the early train or your first flight is late? And you've given yourself less than 2 hours to check in for your flight home. That in itself is too little.

If you want to go to the CT that badly, then do it. But return to Zurich in late afternoon or evening on the 10th, so you wont have to scramble for the flight home.

Yes, it’s crazy. Too many things could go wrong. When we were in Manarola years ago, there was a funeral in town and and almost everything in town, including the train station, closed. Stuff like that happens in small towns! If you miss your flight you have to buy another ticket home. Not worth it.

Is this crazy to even consider doing?

"Crazy" isn't even in the ballpark of how bad this idea is.

Instead of spending all that time traveling to the CT, why not take an easy 1 hour train ride from Zurich to Lucerne? We were in the CT this May then ended up in Zurich for our flight out. We had a few days in Zurich, so one day was the day trip to lovely Lucerne with an afternoon lake boat tour. The other day was taking the Rick Steve's Walk of Zurich (outlined in his book). We thoroughly enjoyed both, but Lucerene more. Save the CT for another time.

Another down vote on the idea from me.

If you must go ; then do your plan a day early and return to Zurich the day before your flight out of Zurich. Otherwise the risk of not getting back in time is too great.

As stated above, this is not a good idea because too many segments could create problems causing you to miss the return flight. There are plenty of beautiful places in Switzerland to occupy your time.

If you have a burning desire to take a long trip consider going to St. Moritz by train. It's the playground of the rich and famous. The town and surrounding countryside is just gorgeous.

Anyway, forget about the Cinque Terre idea and place it on your next trip to Europe

Buon viaggio,.

If the Cinque Terre is on your bucket list, you could consider flying into Florence (and then via train to CT) from Zurich on the 8th, and returning to Zurich on the 10th. We visited both CT and the Berner Oberland in June. CT was more like been there, done that but the BO was like we are definitely coming back here again!