We have traveled a lot during our lives and lived overseas for several years. While, we do go back to some places, going to a new place is my recommendation.
I have been to 70 countries and some countries that don't exist anymore. I loved Venice so much, but after going there the sixth time, I have no desire to return there. I could stay a year in Rome and be happy, but there is still more to see in the World. We have only been to Bergen, Norway, but loved the country. We want to do a North Cape cruise. I love Switzerland as well, but you might find Norway even better.
By the way, here is a lot of must see places, if you haven't been there.
1) China-so much history
2) Japan-more to see than you think and the people there are wonderful.
3) Australia-it would be my choice of where to live if I wasn't an American.
4) Around the Horn of South America is a one of a kind cruise.
5) We love Paris, but there is so much to see in France, if you haven't been to Provence, Alsace or Normandy, do it.
6) The British Isles are amazing, especially in the countryside.
7) Iceland is not to be missed.
I am leaving out a lot of great place, Egypt and Israel are special, but Egypt has some security issues. Also, loved our Russian River cruise. See the World, it is great.