Swiss Saver Pass 8 or15 days?

Hi
We will be traveling through Switzerland this Dec for 12 days/ nights. We start in Zurich early arrival from Australia. Next day onto Pontresina 3, Lucerne 3, Murren 3, Montreux 2 then onto Strasbourg France.
We will be touring as much as possible weather permitting. The Bernina Express and Golden Pass into Montreux as well as mountain trips on various cable cars.
What would you buy 8 days leaving 4 short or 15 and hope we use it enough to not waste 3 days? Any suggestions where to save money if we take 8days?

thanks in advance.

Thank you Annika

I have ordered the 15 day Swiss Saver Pass and hopefully it will be on it's way soon!
Our frustration now is the inability to reserve any trips until after 10 Dec. We arrive in Zurich that day and would have liked to have some specific trips reserved.
Hopefully a new Timetable will be posted prior to December!

Cgh57

Hi Cgh57. Good to hear that you ordered your pass! Just in case you didn't know: most trips in Switzerland don't need seat reservation. This only goes for some special scenic trains, such as the Bernina Express and the Golden Pass. You can read more about this on our seat reservation page and arrange for your reservations there. Such scenic trains can often be booked months in advance, independent of the new SBB timetable. All further regular train, bus and boat trips don't require reservation: you can just hop on and off with your Swiss Saver Pass.