I am going to tour Switzerland from Zurich to Lucerne, to Interlaken, to Thun, and down to Zermatt in early-mid June. Is it necessary to book seat reservations for most trains? I know the Glacier Express is one we will want to make one for, but are there other trains that it’s really necessary for? If we do make reservations and we miss that train, can they transfer it to the next available train pretty easily, or is it pretty strict and we would have to repay for the reservation?