Zurich to Zermatt then onto Italy

Zurich airport station to St Moritz involves train changes at Zurich main station and Chur. Chur-St Moritz goes over the famous Landwasser stone viaduct (seen in all the brochures) and a spiral tunnel to gain height. St Moritz to Italy, you can take the scenic Bernina Express route to Tirano, Italy, either by the actual Bernina Express with advance reservation panorama cars, or a regular train that follows the same route. In Tirano, you need to walk the short distance to the Trenord station and get a train to Milan.

Zurich airport to Zermatt has train changes at Bern (some times you can get a train that skips this change) and Visp. If the weather is nice, the stretch after Bern has some nice views of the Berner Oberland mountains before going through the long Lotchberg Base Tunnel. Again, with nice weather, you can substitute the Bern-Visp leg with a Bern-Brig regional train that uses the old Lotchberg High Tunnel. At Brig, you can either walk the short distance to the Brig-Zermatt station and get a train to Zermatt, or get a regular train back to Visp (just 6 minutes) where you can get the train to Zermatt. This route adds about 1 to 1 1/2 hours to the journey time. From Zermatt to Italy, take the train back to Brig, short walk to the main Brig station and get an EC train to Milan.

Thank you. If you could do only one train - Glacier express or Bernina express which would you do for the sights? I realize the scenic express trains are slower - do you get the same feel on a regional train?

The Glacier Express is longer and so takes more time and is thus more expensive. The panorama cars are only in first class. The Bernina Express is a lot shorter, thus less costly. I've done the Glacier Express, but not Bernina. Also, on the Glacier Express you get a little headset, and when a bell sounds, there is a narration over the headset explaining to sights (multiple languages depending on the channel you are using). Not sure if it is the same in second class. Since it was winter, very few people were in second class, and I was told it can be fairly crowded in summer.
All I can say is. The mountains and scenery are exactly the same from either the Express trains and regular trains. The Glacier Express has to be done with train changes if you want to follow the same route using regional trains, the Bernina trains follow the exact same route directly, maybe making a few more stops.
Also, you want to do these journeys when the weather is clear.