The Glacier express is one of those travel destinations that has become overly popular, so it is often filled to capacity. For this reason, I usually take the regional trains (with the bonus of opening windows). It is difficult to ride ANY train ANYWERE in Switzerland that is not at least somewhat scenic. The Glacier express is a fine route, but I would suggest the following:



This route includes a bus from Lugano to Tirano that will add much more variety to your journey.
The train from Tirano to Chur is The Bernina Express which has large panorama windows, and it too is often full, so you can also opt to take regional trains from Tirano to Chur... some which include a Gormino dining car on the RhB railway from St Moritz to Chur. Yes, indeed a narrow-gauge dining car.