Grüsch is a one pub village, and you will die of boredom and deservedly so if you decide to stay there. There is a very good reason why there is such good rail and bus links, so use them!
You can however stay up in the hotel at the top of mountain, it is pretty much all dormitories but sleeps over 120 people. A one night with half-board and a 2-day lift pass will cost CHF160. They provide live music and bar stays open nice and late. The venue also holds the big end of season finale, be warned, those musical enigmas Right Said Fred closed the season in 2009/10.