What train line goes from Chur to Martigny?
Also, any information comparing this route to the Glacier Express would be appreciated
The Swiss train system can get you from Chur to Martigny. You can see the runs at www.sbb.ch which is the main Swiss train website. It's a 4.5hr. to 5.0hr. journey to Martigny. Most runs will take you through Zurich. Chur is a stop on the Glacier Express.
From Chur, you also have the opportunity to take the Glacier Express to Andermatt where you change trains for Visp and then change again in Visp for Martigny. This route is a 6.5hr. journey. Note that this train is called an "express" but it's not because it's fast. In fact, it's a cog train. It's called an express because it doesn't stop at every stop. This part of the journey will go over the 6,670' Overlap Pass. It's very scenic and a wonderful ride.
The route of the Glacier Express is fantastic, so if you can, take that.
The main route for speed is to go from Chur to Zurich, change trains go to Lausanne via Bern, change trains and go to Martigny. There is also the possibility to change in Bern, go to Visp through the new 35 km tunnel, and then change to Martigny.
These are fast, efficient, and nice scenery, but not as spectacular as the Glacier Express.
Another beautiful route would be to take the train from Chur to Luzern, and then take the Golden Pass Panoramic Train to Montreux, and change there to Martigny.
I would encourage you to break up this trip, if you can, into a couple of shorter days on the train with stops to see some of the places you are going through.
These links will give you more information on these routes:
http://travel.sbb.ch/index.php?module=travelsbbch&func=searchSTS