Have some friends coming for a Euro-visit in late June. Just talked them out of 6 days sitting on a beach on the Dalmatian Coast & into a trip day hiking in Austria.

Can anyone recommend a few towns that are a good place to base ourselves? First place for 2 days, another town preferably in another region for another 2 days, then another spot for last 2 days?

Not sure yet if we'll be traveling solely by trains, renting a car in Zurich then driving, (or training it to Austria, then renting a car?)...

Recommendations greatly appreciated. Many thnx!