It has impacted me most in redeeming awards. The first time I did so, I had been flying a lot for more than five years when US Airways, which was part of Star Alliance, declared bankruptcy, around 2005-6. I wanted to burn my miles promptly, so took a J trip to Europe and F trip to Asia. My first hop was IAD-CPH; I probably wouldn't have included Copenhagen at the top of my list but I was looking for novel (and available) routings. (I will never forget my first time on long-haul J; probably an A330 on SAS, certainly nothing special according to my current jaded standards, but it felt exotic at the time.) I did some Spanair legs, again though MAD isn't where I would have chosen otherwise. It was a great trip; I think I hit CPH, LHR, MAD, BCN, and OPO, mostly Star cities.

When I traveled to Europe frequently for business, I would try to build in a stopover whereever was en route. So I have visited Frankfurt, Munich, and Zurich probably more often than those cities warrant.