Glacier or Bernina?

Welcome ellecll! From Zermatt, you can directly board the Glacier Express to St. Moritz, so that one makes more sense. From St. Moritz, you can travel to Venice via Thusis and Bellinzona, or alternatively catch the Bernina Express tot Tirano first. This is a detour though. All routes can be found through the timetable. As for costs: most Eurail passes cover the Glacier Express except for the leg Zermatt-Disentis. The Bernina Express route up to Tirano is entirely covered; the bus line between Tirano and Lugano is reduced. For both scenic trains a separate reservation fee has to be paid.