11 days in Europe Swiss Alps and either London or Munich.

Why not spend the 10 days in Switzerland? Fabulous country, lot to see/explore. But if you are in the mood for a nature/bustling city combo I would choose London over Munich.

Wherever you decide you want to visit book your ticket into one city (Zurich) and out of your final destination. With only 10 days I might tempted to spend them all in Switzerland, too. Besides Murren (and surrounding villages), Lucerne, Berne, Gruyeres, terraced vineyards around Lavaux (http://www.newlyswissed.com/hiking-the-lavaux-vineyard-terraces-in-spring/) You could fly into Zurich and home from Geneva, and a possible itinerary would be Zurich, Lucerne, Murren, Lavaux, Montreux/Geneva.

I just wanted to see if I can combine a trip to swiss alps with a trip to Austria (Salzburg) and Munich for a more varied trip experience.

Each of your proposed destinations is worthwhile and of interest. But one can argue that you'll find plenty of variety within Switzerland, especially with French being the prevalent language as you get closer to that country. The three German-speaking neighbor countries do have similarities with each other, as well as some individual features. London will be the most different, of course, but if you are already planning to go to Munich and Salzburg, then you need not change your plan. Rather than just aiming for variety, can you identify specific sites of interest at each destination?

You DO know that Switzerland has 3 distinct sections 1) French 2) German 3) Italian. Traveling to Austria for a different experience is really not necessary.