If you want to ski down the mountain, you'll need to make your way to the top of it first. Jump on Grandau Bahn and enjoy the ride up.
You're spoiled for sightseeing choice when spending time in Sankt Gallenkirch. Grandau Bahn is a great place to start here, but there are lots of other worthwhile spots to explore. Silvretta Montafon Gondola, Hochjoch Ski Area, and Zamangbahn are close to the mountainside transportation system and will top off your day nicely.