Hi Ravi -
I'll add my compliments to those of Annika about how well you have prepared.
She has noted the mix- up on the Golden Pass route.
If you go from Luzern to Lauterbrunnen. the most scenic direct route is via the Brünig and Meiringen.
An alternate fast route is to go via Bern and Spiez.
If you wish to go out of your way , and take a longer route, which will include the especially scenic portion of the Golden Pass route, you can go from Luzern to Bern to Montreux ( which, as Annika noted, is not the Golden Pass route). Then you can come back east to Spiez via Zweisimmen, as you mentioned, which is the Golden Pass route.
Since all of your other planning is well quite done, it is likely that is what you were asking about, and both Annika and I did not understand your question.
To make that decision, use the timetable:
If you choose to go via Bern, consider taking the old route ( slower, through the scenic Emmental farmland) between Luzern and Bern. Route via Langnau im Emmental.
The default fast route, which uses stretches of new fast track, goes north from Luzern, almost to Olten , and cuts the corner at Zofingen before heading south down the mainline to Bern. Pleasant scenery, but the Emmental has special charm.
Use the timetable to decide.
This map may help:
<<" From Lucerne to Lauterbrunnen take the train via Bruenig pass and Meiringen and from Bern to Montreux ride the train via Zweisimmen and Gstaad. Both form the Golden Pass Panoramic train route. Which one is more easy with the kids ?
Day 5 Wed
Day 6 Thur
Day 7 Fri
Day 8 Sat
from the base in Lauterbrunnen you can make the following day trips:
*Stechelberg - Gimelwald - Muerren - Schilthorn (Piz Gloria in a James Bond movie) - Muerren - Winteregg
*Grindelwald - Kleine Scheidegg - Wengen
*Interlaken - Spiez - Kandersteg - Brig - Visp - Zermatt (scenic route) and back in a direct train from Visp to Spiez via Loetschberg Base Tunnel. In Zermatt we can go to Gornergrat by cogwheel train or Klein Matterhorn by cable car
If these can be covered in a day, we will have 2 days extra which we kept as buffer for weather. Will this be too hectic for the kids and what can be suggested for the time that we have or any other opinion.">>
I think that you have 2 easy day trips and one full day trip to Zermatt, in 4 days, leaving one buffer. All are reasonable day trips. Schilthorn will leave some slack in that day, depending on when you go. So will Grindelwald - Kleine Scheidegg - Wengen
You could probably include Griondelwald/Kleine Scheidegg/Wengen in the same day as Schilthorn, if you work out your schedule. It helps a lot that you are starting from Lauterbrunnen. Then, indeed, you will have two buffer days.
If you go up to Jungfraujoch, at considerable cost, make sure you have checked the weather with local sources and don't buy your ticket for the last leg (KS to JJ) until the day you travel.
The weather is very difficult to predict far in advance.
You are doing a lot of train riding. Those are nice rides. You might want some walking mixed in. At Luzern, please see the Lion. My eight year old granddaughter spent a lot of time looking at. It really caught her attention. I have attached a page from a photobook that I prepared of our trip in 2009.
She also enjoyed the nearby Bourbaki Panorama. So have all the adults I have taken there.
Not sure about the ability of your older members to do this so-called "Grannies' Walk", above Wengen, specifically in the direction Männlichen to Kleine Scheidegg, but it is very easy and wonderfully scenic: