Bernina express ' Little Red train'

For a day trip? Probably not unless you are someone who really loves riding trains. If you are not going to spend any time in Switzerland, I'd give it a pass. If you are looking for a day trip, try Varenna on Lake Como or Stresa on Lake Maggiore

Sally, The Bernina Express (or more exactly the Bernina Pass route over which the Bernina Express scenic train plus hourly normal trains run), runs from Tirano to St Moritz.
Tirano is some way from Milan, you have to first get an Italian railways train to Tirano.

Yes, this is a most spectacular train trip, over the Alps, and well worth it.
But, to do it as a day trip from Milan you would have to come back again, and it would be a very long day.
The best way to do this route is as a detour if you are going from Italy to Switzerland (or vice versa). You then continue on the train to Chur, this second part is also spectacular.
If you only have 3 days for Milan I would say, regretfully, leave it to next time. Instead take a day trip slightly north from Milan to one of the lakes. For example Stresa on Lago Maggiore, or Lugano on Lago Lugano.

Information from the railway company which owns the route: https://www.rhb.ch/en/panoramic-trains/bernina-express

In July Cinque Terre might be crowded, unpleasantly crowded.
Around Milan you've got other wonderful destinations, for daytrips or staying. Rough, but very historical and interesting Genua (Genova). And elegant and no less interesting Turin (Torino). Both 1,5 to 2 hrs away, depending on the type of train.

Bergamo is a nice daytrip from Milano - about an hour each way by train. Take the shuttle bus from the train station to Bergamo Citta Alta.

Is 3 days enough for Milan? Most would say it's too much. First, Milan is not always liked by visitors - it doesn't conform to what they want from seeing "Italy." I happen to like it, but even I would say 1-2 days is enough.

Unless you have a special interest, you're probably better spending less time in Milan and more in other places. Milan is the hub of the northern Italian rail network, with easy access to lots of places, depending on your interests.

Here's Rick's list of Milan attractions (click "At A Glance" to see his list). See how many appeal to you, then decide how much time to spend in Milan: https://www.ricksteves.com/europe/italy/milan

Thank you all for your feedbacks. We were thinking of some day trip from Milan like maybe lake cuomo ?

Varenna is only one hour from Milan on the regional train (schedules at www.trenitalia.com but no reason to book ahead) and makes a good base for ferries to neighboring towns.

P.S. Even starting from Varenna, continuing toward the Bernina Express route is probably too long, e.g., 4 hours one-way Varenna-St. Moritz or 6+ hours Varenna-Chur.

Thanks Laura. If I understand correctly we can take the train to lake cuomo and ferry to Varena ? We plan to stay for 3-4 days in Milan to do side trips. I will post separately regarding recommended side trip from Milan.

Sally,

I thought you had just had a typo earlier, but I see you repeating the errors. Spell it as you like, but if you start doing research or needing train times or ferry boat times you will need to spell correctly or you won't find what you are looking for.

It is Lake Como, with the major town at the south end of the western fork (with a train station and boat terminus) being Como. Cuomo was a mayor of New York.

Varenna has two "n"s. It is a lovely place, very quiet and very beautiful. It also has a train station and boat dock.

You could take the train from Milano Centrale station in Milan to either Como or Varenna and ride the boat from one to the other, or spend all day by taking the train to Varenna, explore there on foot, take the ferry to Bellagio, explore there on foot, take the boat the length of the western arm to Como and either turn around and see it all again from the other side (my choice - always, I adore the views and take so many photos) or get off at Como and get the train back to Milano.

Oh sorry . Thanks Nigel for the correction . Appreciate it!