Start
Gletsch
Here you can go up the Grimsel pass and Susten or you can take the Firka pass.
Innertkirchen
here you can take the Brunig pass home back to Zurich if you want...or if weather turns nasty. But I like to do the Susten now as well.
Wassen
From here you make your way back to Zurich. Can take a detour on way home :-)