Jul 6, 2018 - 7:08 PM
Based on my experience in 2015, I would suggest you look a combination of the half fare card and the Bernese Oberland pass.
Seventeen days should make for a wonderful holiday.
The travel resources you need and/or links thereto should be on this wonderful site.
Planning is half the fun and PPPPP always applies; prior planning prevents poor performance.
Ejoy your travels!