We will be arriving and departing Interlaken by car for 3 full days there. Is any choice of passes worth the money for traveling up both mountain tops as well as to and from various towns above Interlaken.
Julie if you do the maths you may find the half fare card at 120chf for one month the best bet.
Ditto Pauline. Round trip fares to both mountain tops will be approximately 290CHF ($313.00) from Lauterbrunnen. 1/2 fare card costs 120CHF. Half fare to the two mountain tops is 145CHF. 145CHF + 120CHF = 265CHF. You're ahead 25CHF. As you ride any additional transportation in Switzerland, you'll be farther ahead.
Thanks to all for your responses.