<<"my friend and family is travelling from milan to spiez on 23rd. they aretwo adults and 3 kids. they have a swiss pass valid for 6 days from 23rd. whch is the most economical option for them to reach spiez.">>
Hi Jackson1216 -
Welcome to the Forum.
I assume your last sentence is a question?
If so, the answer depends on which of the many Swiss passes for rail travel they are using.
Please check this link:
Arno and Annika ( the moderators) are the experts on rail passes.
However, I can get a start.
Do you mean a "Swiss Travel Pass" ? If so, any of the public transport trains in Switzerland ( except special and privately run excursion trains such as the one to the Jungfrau in the Alps) require no additional payment .
So, they will have to pay for the Italian segment from Milano to wherever they cross the border. After that, the Swiss Travel Pass pays for the rest.
The usual route is to go via the Italian town of Domodossola, then through Brig in Switzerland.
A map may help:
and the timetable:
From Brig to Spiez, there are two routes. The fast one goes through the new "basis" tunnel under the Alps. It is the fastest and most boring.
If your friends have a little extra time, they will find the old route to be much more scenic on both sides of the Alps. It climbs the side wall of the Rhone Valley before going through the old, shorter Lötschberg tunnel. It then descends through the scenic Kander Valley. The train has a name - "The Lötschberger." and does not require reservations or extra costs.
As they look out the windows of the train ( sit on the left) going up the valley wall they may see hikers on the "rail trail" which parallels the rail line and is visible in many places.
The timetable shows one route or another, depending on how you use it.
In order to force the time table away from the fastest route, and to get it to show the old route, enter "Kandersteg" as a "via" or "connection" in the option available hen selecting a route.
Hope that helps, and that I understood your note.