Via Zurich HB - Munich to Zurich by ICE (4h approx) then Zurich to Grindelwald via Bern (2h 40m); use Eurail Pass. Total travel about 6h45m including transfers.
Included in Eurail Pass + seat reservations (~EUR15 per train segment per person)., 6h45m
Exciting mountain activities including alpine coaster and Trot bike on marked trails; great for families; open 9am-5pm; book equipment online for best prices.
Travel via Zurich and Milan: Interlaken to Zurich (2h), Zurich to Milan (3h40m), Milan to Rome (3h); use Eurail Pass, book seat reservations early (approx EUR30-35 per segment). Total travel ~9h+ including connections.
Included with Eurail Pass + reservation fees, 9h30m