Hi Shilpa, and welcome to MySwissAlps!
If you want an easy and convenient solution, I would probably go for an 8-day Swiss Travel Pass for each of the adults. When buying the passes, you can also order a free Swiss Family Card, which will provide free travel for your 15-year old. The 5-year old will travel free without the need for any type of ticket.
An 8-day 2nd-class Swiss Travel Pass used for only 6 days would cost an average of CHF 66.33 per day. This compares with an average cost of CHF 67.50 per day for a 4-day 2nd-class Swiss Travel Pass, which would not cover your whole stay.
While an 8-day Swíss Travel Pass would be a convenient option, whether it is also the most cost-effective option can't be known without planning a detailed itinerary and costing it, including all trips by train, bus, boat and cable car. Then you need to look up the full-fare cost of all these planned trips and compare the total cost of separate tickets with the cost of doing the same trips with the Swiss Travel Pass, Swiss Half-Fare Card etc.
You can find fares in the Swiss Timetable.
(Use the timetable on the right with the red SBB logo)
It is important to be aware that the fare shown for any trip in the Swiss Timetable defaults to half fare, as most Swiss residents will have a Half-Fare travelcard which entitles them to this discount. Your calculations need to be based on full fares, which are double the default fare that comes up.
There is information and a spreadsheet here to help you:
www.myswissalps.com/tr ain/ticketspasses/prac tical/chooserailpass
>> Will we need additional reservations to make in any section?
Reservations in Switzerland are the exception rather than the rule. The only trains on which reservations are compulsory are
- the Gotthard Panorama Express
Reservations are always an additional cost, regardless of what sort of ticket or pass you are travelling with.
This link might also be handy:
www.myswissalps.com/tr ain/practical/howtotra vel
When planning day trips from your base cities, be sure to use the Swiss Timetable (link above) to find out travel times. Daylight will be from approximately 6:00 until 21:00.