Swiss Train

Every rail line in Switzerland has at least one train per hour. So, just decide where you want to go, and then look up the trains/feeder buses to get you there.

There are many popular areas in the Swiss Alps, it is a matter of choosing one. If you have only 4 days you really only have time for one place, and your choice is partially dictated by where you are entering and leaving Switzerland.

• Berner Oberland (Grindelwald, Lauterbrunnen, Wengen, Mürren etc.)
• Luzern and area
• Zermatt
• Graubünden and Engadin (valley)
• Plus many, many others.

I think the OP wants to know what kind of travel pass or discount card is best to get for a four day trip.

From other threads, May 26 to June 9 for the whole trip, 2 adults and a 5 yo.

Also from the previous thread:

For Switzerland, no one will criticize me for recommending Lauterbrunnen, Muerren, or Wengen in the Berner Oberland area. It is a common recommendation for good reasons. The ticket from Basel, where you would most likely enter Switzerland from the Black Forest, is 80 CHF per adult and 40 CHF per child. Given that you will probably want to ride some of the cable cars while you are there, that will add up. The ride from Muerren to Schilthorn and back is 80 CHF per adult, so all in all you will spend at least 240 CHF per person. So if each adult gets a Half Fare Card for 120 CHF, all tickets thereafter will be half price. You can also get a free Family Card, and your 5 yo travels with you for free. Buy these at your first entry station in Switzerland.

I guess I'll stand by that.

Whether a pass is a good idea or not, and what pass is best (if any) depends on where you are going and what travelling you are doing there. There are basically three options:
1) Pay full fare for everything.
2) Buy a half fare card, and pay half fare (= child fare) for everything.
3) Buy a Swiss Pass, and everything is covered except the higher mountain railways, for which you get a discount.

Plus, there are two further wrinkles. If you are staying in one area, there are local passes which provide more extensive and cheaper coverage of an area, but you then need to add on tickets to get from the border/airport to that area, and back again. If you have children, there are various options to get very cheap or free add on tickets if they are travelling with you.
All fares and details on the Swiss Railways (SBB) website: http://www.sbb.ch/en/leisure-holidays/holidays--short-breaks-in-switzerland/swisstravelsystem.html

To work it out, you need to decide where you are going, list all the trips and make a spreadsheet, happy calculating!