Best train options from Lucerne to St. Moritz

My friend and I (83 and 73) leaving Lucerne 5th October 2015 travelling to St. Moritz on Glacier Express then leaving St. Moritz 8th October Bernina Express onward journey to Venice - Is it better to get a "pass" ( what type) to cover these two journeys - other trips/transport if we decide to - or get separate tickets - costs if possible....thanks for any advice.

Hello Winnis, and thank you for joining MySwissAlps!

In most cases, it's more economical to buy a rail pass. It's hard to tell which one's best though, as it all depends on the specifics of your itinerary. For example, how long will you be in Lucerne before heading for St. Moritz? Do you intend to make day trips from Lucerne and from St. Moritz? And if so, which? You may start off by reading this guide and looking at a 4 Swiss Travel Pass and a Swiss Half Fare Card, for example.