@ben I used to live on Club Street, was back there fo a few weeks in Feb. You are possibly too early for Lenzerheide or the riding around there using the mountain railway from Chur. When I was in Verbier 2 weeks ago kids where riding the trails from 1650 down to the valley and where allowed on the bubble so its possible you can do a bit of that locally. Have some friends who go to Wessen might be worth a look.
Do you have SwitzerlandMobiloty app, very useful walking and mtb trail highlights (most highlighted walking trails are good for riding eg many of Verbeir enduro trails appear as walking not mtb which can be a bit fireroad orientated)
If I am in town I’ll drop you a note if you fancy a beer