Hi, I can only comment on Switzerland. I travelled throughout Switzerland for 6 months (staying put at places though, as it's such a tiny place it doesn't take long to see the whole country
), by myself when i was a 22 yr old female and i had no problems. It's always impossible to say, but generally Switzerland is a pretty safe place and i didn't get harrassed at all.
My favourite places to visit are Luzern, St Gallen and Bern - they are all in the German speaking part of Switzerland and are very quaint, pretty towns. Interlaken (although a bit tacky) and Grindelwald are also great places to visit if you plan on doing some skiing/snow sports.
As it's been mentioned, Switzerland IS very expensive - in fact the only thing that is cheap is the chocolate (supermarkets like Migros and Coop have great tasting home brand blocks)!! You'll probably find you run out of money before you get to do everything you want to do.
Best of luck! 