Hello Boahoihues42
How many days does your trip include in total?
Also, I always wonder why some tourists call it Swiss Pass while, I believe, the ticket you envision is the Swiss Travel Pass, eh?
If you are unsure what pass, as a general advice, the Swiss Half Fare Card plus individual half fare tickets, or the Saver Day Pass for longer trips, are never wrong.
In your case, the Swiss Half Fare Card in combination with the Berner Oberland Pass could offer great value. Or, the Swiss Half Fare Card and the Jungfrau Pass. Have you had a look at them?
Also, why did you choose Interlaken as a base?
Kind regards,
Roland