Advice for a 50-day trip? Since you hesitate a bit my first advice is
do it! The next occasion for such a vacation could be ages away! And it will be very interesting.
My second advice is: don't go location hopping. It can make your trip straining and you'll end up throwing away time in airplanes or trains that you could invest for sightseeing and exploring Europe. It's a matter of personal taste but I would travel every second day at most.
Spontaneity vs booking in advance is another personal preference issue. Once you've decided which parts of Europe you want to visit mostly, you can mix both methods, too, and just set your distant travels that probably are by plane. So you still can be flexible while traveling some parts (especially the regions with very good train infrastructure, p.e. mainland Denmark, Austria, Germany and Switzerland).
Where to go is up to you but suspected antipathy towards foreign looking people is a bad guide because this shouldn't be a problem. "Something of everything" is a reasonable start for such a long trip, in my opinion. But is this a strictly geographical credo or are your experiences meant, too? (P.e. I for one wouldn't spend a single day at the beach because you can do this in America just as well, I'd focus on the things that are specifically European: sights, cuisine etc...)
Sporadically there are some good threads in ATOT about travelling Europe. An older one is
this.
If you have specific questions about Switzerland in general or plan to visit Zurich, you're welcome to drop me a PM.