In Switzerland, most trains do not require a seat reservation. Trains on which seats can be reserved are marked with an “R” in the timetable at sbb.ch.
Within Switzerland, no surcharges are payable on national InterCity and InterRegio trains. Panoramic trains such as the Glacier Express and Bernina Express as well as certain bus routes (the Palm Express) are mostly subject to a charge and/or require advance reservation and should be booked as far ahead of time as possible. These are marked with a “Z” in the timetable at sbb.ch.
Seats can be reserved at sbb.ch, online on the websites for the relevant means of transport or at the railway station ticket counter directly.