Just wanted to update the post with our experience from the recent trip.
Emmental, where we stayed, is stunning! The drives to Lauterbrunnen Valley & Luzern from Signau were quite special.
Sounds like a cliche, but pictures don't do justice to Lauterbrunnen Valley. We thought it was stunning. We hiked from Grutschalp to Winteregg. Note that the path is slightly upward sloping and my mom & mom in law found it slightly challenging. But the views were quite grand (this was the grandfather's walk). From Winteregg we took a train to Murren. It's nice little place, the houses are overflowing with flowers! From there we took the cable car to Gimmelwald and enjoyed drinks at a restaurant facing humongous cliffs, quite special (it's right next to the cable car station). From there on, we continued towards Stechelberg, an incredibly steep ride! Quite thrilling. From Stechelberg we hiked to Trummelbach falls (about 3 kilometers), took us an hour and fifteen minutes. The walk was amazing. There were also facilities for BBQ along the river! The mountains look so grand from the valley. I would highly recommend walking all the way to Lauterbrunnen if anyone has time & energy.
The next day we visited Luzern. An amazing town. Walk by the lake promenade is quite peaceful.
On the last day we visited Wengen and hiked Mannlichen to Kleine Scheidegg (grandmother's walk). The scenery is incredible. There was some snow even in September! But wasn't cold. The three big mountains were all snow capped. Quite a sight to see them so up close. There is only one toilet on the 4 mile trek and lets just say that you would use it only when there is an emergency. There is a restaurant when you arrive at Mannlichen, it has all the facilities, plus play area for children and awesome views of the valley. From Kleine Scheidegg we took the train down to Lauterbrunnen. There are many walks when you reach Mannlichen. We took the Panorama Walk. There is also Romantic Walk and the one that goes all the way down to Lauterbrunnen! For four adults the tickets cost EUR 242 - round trip. Well worth it.
The drive past Brienz was amazing. I would recommend stopping by at Spiez if you have time.
I thank everyone for their tips. It really helped me plan in quite some detail. I would like to summarize a list of all the places mentioned in this post.
Lauterbrunnen Valley & Around
Lauterbrunnen valley, Trummelbach falls
Truemmelbach falls to Stechelburg hike - 72 waterfalls walk
Murren (Grutschalp lift to take the train to Murren is wonderful), Alpenruh restraunt
Murren - Allmendhubel - cable car
Northface trail from Allmendhubel to Murren - 4 miles
Murren to Gimmelwald - cable car
Gimmewald to Stechelberg via cable car going to Trummelbach falls
Gimmelwald - working farm/cheese making
Mannlichen to Kleine Scheidegg view of the three mountains (Monch, Eiger and Jungfrau) - Grandmother's walk
Brienz lake tour to Lauterbrunnen
Murten - lake side town
Gruyères - Cheese/chocolate factory
Bonigen - decorated/carved houses
Ballenburg - open air museum
Lucerne - lake & city