Bernese Oberland

If GF looks clear enough, keep the 08:35 train plan.

If clouds may lift later, delay train+gondola by 1–2 hours, skip/compress optional activities

If GF is rainy/poor, stay low: Interlaken town, lakefront, and/or a short Lake Brienz outing

Use SBB day-of

Optional coffee: EigerBean if timing works

First Cliff Walk + viewpoints

Optional paid activities: First Flyer / Glider, mountain carts, trotti bikes

If descending early and weather still works: Pfingstegg toboggan, Glacier Canyon, or Pfingstegg playground.