I've been thinking of going Chur to Andermatt then to Lucerne. But looking at rome2rio it shows that you have to go via Goschenen and trains from there only leave every 2 hours. Also, it shows the train starting in Hospental rather than Andermatt. We'll be getting the Glacier Express from Chur to Andermatt, so Hospental isn't very convenient. It seems that this isn't a sensible route to take. Am I right?
The alternative is to get off the Glacier Express in Brig and go to Spiez, which is a very quick and direct trip. This was my original plan, but then I started to think I'd like to see Lucerne.