It is also the only Great Lake located entirely in the United States. Lake Ontario: Ontario is the Huron word for lake of shining water. This lake is the smallest of all the Great Lakes when measured in surface area (7,340 square miles / 18,960 square km).
The Swiss franc (CHF) is the only official currency in Switzerland (and in Liechtenstein). The franc is the only currency accepted everywhere. The Euro is the currency in the neighboring countries Germany, France, Italy and Austria, and in many other European countries. Nevertheless, you can pay with Euros in many shops, hotels, rail stations and gas stations in Switzerland. This is convenient if you're only in transit or only stay for one night.
They are making a lot of money off of taking dollars. I would bet that it is the same with your hotel. They will accept USD or Euro as well as CHF, but you will very likely pay the least if you pay in CHF. I cannot speak specifically on Gimmelwald, but I would not expect every restaurant and ski resort to accept Euros. I would suggest using CHF or a debit/credit card.