The Swiss Travel Pass is an all-in-one ticket offered by the SFF for most forms of transportation in Switzerland. It also comes in a flex pass (choose the days you travel) and a youth pass at a discount.
The pass can be purchased in 3, 4, 6, 8 or 15 consecutive days of travel. The flex pass be purchased for 3, 4, 6, 8, or 15 selectable days of travel and is slightly more expensive (675 vs 706 CHF for 15 days in 1st class).
There are two classes of tickets: first and second class. Second class train ticket for 8 days is $420 vs $666 for first class. First class has deck access on steamer boats, seats tend to be larger on trains and less crowded.
The pass includes discounts on museums and high mountain lifts, but discounts are only available on counted travel days for the given pass. For a flex pass that would include the days picked as part of the allotment of days.
The Swiss Travel Pass can be bought 30 days in advance.