I've been in winter and had a great time as long as you aren't there to do anything like shops. Just be aware that if the ferry shuts down, you will need to find a contingency plan. When I went, there was one last ferry for the day before they were cancelled for weather (it wasn't snow but something else like high wind). March is still fair game here for crappy weather in a bad year.

I should also say I paid next to nothing for accommodations since it was off-season. It probably wouldn't be worth it if you are still getting charged $400+ a night.