Zurich - Bernese Oberland - What Next to do with two 14 year old girs?

Hi - My family (husband, two 14 year old girls) and I will be flying to Zurich on July 23 from N. America, arriving there Sunday, July 24. We are to meet friends in Grindelwald for 4 days of hiking on July 25, ending up in Lauterbrunnen. We don't have anything planned after that, apart from having to be back to Zurich by August 4. We leave Zurich Aug. 7.

We would love suggestions on:
- Should we rent a car or train to Lucerne on Sunday after we arrive - we'd love to see it
- How best to get from Lucerne to Grindelwald?
- Ideas after Lauterbrunnen with two 14 year old girls
- Money is an object, so probably 3 star at best

Thanks very much in advance for any and all reccommendations.

Should we rent a car or train to Lucerne on Sunday after we arrive - we'd love to see it

<-- Train.

How best to get from Lucerne to Grindelwald?
See http://www.goldenpass.ch/CMS/default.asp?ID=359</i>

The trummelbach falls is a nice flat ish walk along the valley floor, ideal if the weather's closed in. It takes about 30 min to see and walking there and back. If you have a pass then there's always the steamers on either lake brienzersee or thunersee which is again ideal if the weather's closed in. Alternatively you could always do a hike and gondola combination; hike one way, get the gondola the other way.

Money is an object, so probably 3 star at best
Pass on this bit, sorry, I camp!

Edited by: Fwoggie

A fun day out is the Ballenberg Museum which you can get to from Interlaken by train to Brienz and then a short bus ride to the museum. It is family orientated, has lots to do and see and if your time is limited in Switzerland, it gives a good overview of the culture and heritage Switzerland has to offer. Two 14 year old girls would certainly not be bored there.
Where will you be staying? In the area of Interlaken, Lauterbrunnen, look for B&B's and also ask for family rooms which are good value for money. Book early.