I'd also suggest you keep in mind any activities you might be planning during your visit and be sure that they are covered. I'm thinking of things like skiing , rock climbing, horse riding, etc.
If you use one of those price comparison sites , they make it pretty easy to compare what is covered and what is not. It can be surprising to see that some policies don't cover anything, even things you wouldn't think of like boating. Some of them even add on extra exclusions like "you aren't covered for any accident if you've had a drink, or if you are doing something illegal." Often the most expensive ones are the worst.