I will be traveling on Glacier and Gotthard express from 18-21 May with family. How important is to reserve the seat, I will be traveling with STP.
You can't travel on either of those trains without a reservation but you cam follow the same routes on regular trains without resrvations.
Rockoyster is correct. For the best experience I'd recommend taking the Express trains. For the Gotthard Panorama Express I recommend 1st class.
Planning your trip is much easier with a free MySwissAlps account. Learn all about Switzerland and get in touch with us quickly if you have questions.
Let Swiss travel consultants create a customized itinerary. They will book your entire trip.