PalenQ

Continuing examples in the BOB where a Swiss Pass will be a better bet than a Swiss Card:

A Boat Trip on Lake Thun

If you get tired of hiking, etc. and have a half day to burn or want to do an excursion down to the lakes the wedge Interlaken on the east and west

then it's easy from Wengen, Lauterbrunnen, Grindelwald and even Murren or Gimmelwald to hop down to Interlaken and at the Interlaken-West station hop on boats that putz around Lake Thun - taking either the 1.5 hr or so cruise to Thun, Spiez or Oberhofen or other cutesy lake town and hop the train back to interlaken.

I love a late afternoon summer cruise when the sun gloriusly illuminates the Jungfrau Massif that looms over the lake making just a magnificent panorama - especially from the middle of the lake

Oberhofen, just over an hour away is a popular disembarkation point to explore and then hop back on one of the frequent, in season, boats.

Oberhofen is a cutesy with its old castle protruding into the lake. The towns houses and buildings are gaily colored - it is a picture postcard setting.

Then you can take another boat to Thun, a large city but very cute too - it has a roaring river running thru it and flower-bedecked old wooden sluices in the town centre. It's got its own imposing castle and a pleasant pedestrian shopping district

You can hop trains from Thun back to Interlaken in about 20 minutes.

Or take the boat or train to Spiez, on the way back to interlaken to poke around this very dreamy town with a great castle on a hill carpeted in vineyards perched high over the lake. Great panoramas here too. Again just a few minutes back to Interlaken by train.
there is a fine hiking route the few miles between Thun and Spiez if you want to go some gentle walking along a ridge overlooking the lake.
All conveyances Wengen, Lauter, Murren, etc. and boat and all are covered 100% by a Swiss Pass (first class gives you seats on the openair upper deck; 2nd class in the covered portion but that is fine too) if you use say your 3rd day on a Flexipass - even at 50% off with the Swiss Card it would amount to way more than the $19 difference in price between pass and card. and no need to queue for tickets, etc. If you're coming from Murren or Gimmelwald savings are even greater.
So if you are going to be in the BOB several days i would heartedly recommend using the 3rd day on a Swiss Pass to go down from the hills and experience the equally appetizing lakes Brienz or Thun - and a reason a pass can be much better than a Swiss card.
And even on the day you arrive in BOB you may get there at noon say and have enough time to hop on the boats for a few hours relaxing cruise - in that case being covered 100% of a Swiss Pass because you'd be using it to get to Interlaken area. With a Swiss Card you'd have to pay 50% and right there goes the $19 price difference between card and pass.

More excursions next time

PalenQ

<Before making assertions like some of the above, how about putting actual figures on paper and running a break-even analysis. The cost of the Pass above the cost of the Card, or the half fsare card often outweigh the benefits if most of the travel is within the Berner Oberland region>

Please let me make clear that if all the travel were within the BOB itself then neither the pass nor card would usually beat the Half-Fare card or no card at all like bob recommended (if weather is crummy)

I owe Bob Brown an apology because i misread or did not read right his poast i copied above in this post - that it was limited to travel just within the BOB or Interlaken and up area. I was thinking of someone who will go from Zurich or Geneva airports or borders to the BOB and then the Swiss Pass is nearly always better than the card.

And the reason i kept detailing day trips is more because once i started i'm continuing since someone on my Scenic Swiss Trains thread asked just about day trips from Interlaken so i will continue a bit more.

BUT BOB BROWN IS RIGHT - IF YOU DRIVE TO THE INTERLAKEN AREA THEN EITHER THE HALF-FARE CARD OR NOTHING AND BUYING PT-PT OR PERHAPS THE JUNGFRAUBAHNPASS OR BERNER OBERLAND PASS WOULD BE BETTER. SORRY BOB FOR MISUNDERSTANDING - ACTUALLY MISREADING YOUR Q. MY FAULT. IF YOU SEARCH FOR BOB ON FODOR'S YOU WILL FIND AN ABSOLUTE WEALTH OF INFO ON THE BOB, TRANSPORT, HIKING AND MORE.

Now back to excursions from Interlaken and efficacy of pass or card or Half-Fare card - i suggest if coming to Interlaken by train the 3-day Swiss Flexipass is better deal for options and most than the other two