Glacier Express, then Florence: which is the best route?

Definitely St Moritz because from there, you can travel on the Bernina railway, which is simply stunning. It takes you to Tirano, then it's a local train to Milan, and a high-speed train to Florence, so only 2 connections (same as from Zermatt).

Total travel time from Zermatt to Florence might be 1-2 hours shorter, but it is still long and you lose a lot on scenery.

EDITED to add that indeed, doing Glacier Express + Bernina railway is a lot of scenic train travel. Not sure I would have the patience, personally, but others may find it relaxing.

By train, from Zermatt. 2 connections to Florence via Visp/Milan possible if you time it right, otherwise 3. Max 6 hours travel time. From St Moritz it's more like 7 hrs +. As mentioned, more scenic from St Moritz, but it depends how much you like sitting on a train, especially if you'll have just done Glacier Express.

Thank you! We'll spend the night after the Glacier Express.. but I'm still worried about a full day of train travel the next day. Is it worth it to take the train to Zurich, then fly to Florence? We love trains, but it might be a bit much for our companions.

Dealing with the airport and flying will actually take longer :) so I would go for the train, probably the quicker route from Zermatt then. Less stress and drops you in central Florence. And you'll probably do tons of walking in Florence, so it can be nice to have a "train day" before arrival (to convince your friends) - just relax with a book or music, sit and look at the scenery!

Taking the train to Zürich airport from either Zermatt or St Moritz takes about 4 hours, so it is absolutely not worth it.
However, two questions:
- is the Glacier Express an absolute must for you? I find that the combination of Albula + Bernina railways, from Chur to St Moritz and on to Tirano, already provides an outstanding scenic railway experience.
- Linked question, are both Zermatt and St Moritz must-dos? The Glacier railway is the most logical connection between the two, but it is time-consuming.

Yes, the Glacier Express is an absolute must, and then we must get to Florence. But it's looking like two long days on trains..

More than 2 long days, as just getting to Zermatt or St. Moritz the day before your Glacier Express will take a half day.

I understand the Glacier Express is essential for you, but do you absolutely need to do the whole thing? The section between Brig and Disentis is considered by some to be the most scenic; I would add the stretch east of there heading to St. Moritz. From Brig to Zermatt it is lower elevation and less “alpine” in scenery, until you get to Zermatt (if the Matterhorn is visable).

If you started in St. Moritz and went as far as Brig, you would have an easy trip 4-hour from there to Florence via Milan.

But maybe Zermatt and a chance to see the Matterhorn are essential too.

I'm going to agree with Balso. I did the Glacier Express from Zermatt to Chur one day, and the Bernina Express the next day to Tirano. (From Tirano I only went as far as Varenna.)

Both trains were amazing. The scenery will keep you riveted to the windows.

Comparing the times for the train, and all the time you need for the plane (security, checking in, etc) it is close but slightly less for the train.