Jan 22, 2016 - 3:50 PM
in reply to AugustW
If this is actually all the traveling (so no cable cars, boat trips, etc.), then a Swiss Half Fare Card will not save you money (see here for how to verify). I'd recommend regular tickets for the adults and two Junior travelcards for the twins. These cards are available online, but only combined with other rail passes. Separate ones can be purchased from staffed rail stations in Switzerland.
An additional way to save some money is Supersaver tickets for the adults, but beware of their limitations (fixed departure times, no refunds).
I hope this was useful. Enjoy your stay!