"If we opted to do train, it would be only from Zurich to Lauterbrunnen
and back, and then from Zurich to Konstanz, Germany. Do not believe
Swiss Pass cost would be worth that."
Just to emphasize and amplify Ken's correction. Unless you are walking everywhere from Lauterbrunnen, you will be taking trains, buses, lifts, and funiculars to get around the region. The Swiss Pass covers all fares on these as high as Mürren on one side of the valley and Wengen on the other. It also gets you half off everything higher than these towns, with the exception of the train up to the Jungfraujoch (only 25% off that run above Wengen; when I went in September 2014, it was about 130 CHF with the Swiss Pass). As an added bonus, for fully covered rides there's no need to buy tickets; you just hop on and show your pass, which saves time.
If the Swiss Pass doesn't suit, the Half Fare Card may. It gets you half off on anything that moves in the country, but you do have to buy tickets before boarding.
Another bonus of either the Swiss Pass or the Half Fare Card is that you are not restricted to the Early Bird departures, but can go when you like. The weather is usually best early in the morning, but in case it isn't, you aren't stuck. You also aren't stuck if you oversleep and miss the discounted departures.
If the weather is iffy or if you don't want to spend the money on the Schilthorn, by the way, the Allmendhubel is a good alternative. It's not nearly as impressive as the Schilthorn/Birg combo, but it's also far cheaper, and still very worthwhile.
Investigate prices on the Swiss rail site link given by Chris, and remember that the default prices shown on that site are WITH a Half Fare card. Once you start adding up your definite trips, it's highly likely that some form of pass will pay off. The Half Fare card is easy; if your total travel adds up to more than twice the cost of the Card, get it, since you can't go wrong. The Swiss Pass is harder to calculate.