Mar 2, 2016 - 6:25 PM
The Swiss Travel Pass offers better value for your trips in Switzerland, especially since Eurail passes only provide a 25% discount on all trips south from Interlaken. Since you'll be staying in Mürren, using a Eurail Pass would mean that you'll pay 75% of the regular price for local trips, which is quite expensive. Please refer to the "validity" section of our Eurail Select Pass page.
The Swiss Travel Pass offers free traveling as far as Mürren/Wengen/Grindelwald, and 50% off most cable cars and mountain rides in this area. Schynige Platte is even entirely for free. So a Swiss Travel Pass plus either regular tickets or an additional pass for the Austrian portion of your holidays seems to make more sense than a Eurail Pass.
I don't expect Konstanz to be included in a 2 country pass for Austria and Switzerland.