Hi Bjarni & Soffia
As mostlybytrain already mentioned, the concept of Bungalows is not very common here. We are living in a hard climat and houses can be heated and protected better. You can book a holiday apparment directly on the St. Moritz website www.stmoritz.ch (also in English). Most appartments during the high season are rented for one week at least, usually starting saturday. And then, there is enough to do also filling one week easily. If you can not find an appartment for just 3-4 nights, try a hotel with a family room or 2 connecting rooms. This safes you time with shopping for everything you need in an appartment and you have more time for activities.