swiss pass?

Use www.sbb.ch to estimate point to point costs (double the initial displayed price as the site assumes you already have a Half Fare Card). Compare the cost with a Swiss Pass. You will probably find either the Swiss Card for 199 chf, or the 30 day Half Fare card for 120 chf will be your best value. Even with a Swiss Pass, you still get only a 50% discount at most on private mountain trains and cable cars. The Swiss Card and Half Fare Card still get you these discounts.

A Swiss Pass must be shipped to you if ordered at home, or you can buy it in person at Zurich airport train station. The 4-day flexipass at $330 per person looks equal to or cheaper than buying your 4 longer rides at train stations there, and the pass will give you 50% discounts on all transport in between those 4 counted days. It's also adds up about the same as a Half-Fare card plus half of my $350 ticket estimate.

The 8-day consecutive pass for $411 gives you more coverage on the in-between days for lower-level trains, buses, trams, boats, and museums, but it looks like you don't have many in your plan. Covered transport from Muerren to the other side of the valley at Wengen, which are the "high-point" limits for full coverage there, costs about $20 each way. For the Berner Oberland, you can see costs summarized on the map in that chapter of Rick's books, p. 151 in Switzerland. The Half-Fare card does give you a better discount between Wengen and Jungfraujoch, if that train is on your list.