Be aware that Schruns offers a wider range of nightlife than the smaller and sleepier Tschagguns, where a drink or two beside a flickering fire in any of the resort's hotels might be the most popular after-ski activity.
In Schruns, the previously recommended Löwen Hotel offers more energy and a greater number of options than anything else in town. Its dance club, Löwen Grube, is open nightly from 9pm to at least 3:30am from December to late April. The evening invariably begins with a spate of live Montafon Valley evergreen music that's performed from 9 to 11pm. After that, disco rules till closing. Entrance is free. A calmer, more contemplative bar that's undeniably cozy is the Löwen Hotel's Kamin Bar.
There are no equivalent dance clubs in Tschagguns, although if you prefer something a bit quieter -- or a bit earlier in the afternoon -- there's a fire blazing in the Montafoner Hof's rustically appointed and very charming Kaminstube whenever temperatures justify it. It's open in winter daily 3pm to 3am.