Switzerland Forum: 7 day Switzerland trip need itinerary help

I am planning a trip to Switzerland for 7 days... need to end up in Geneva for a meeting (last 3 days of the trip). One stop that I absolutely want to do is Zermatt / Matterhorn.

Should I choose Zurich or Bern as the other city? is one city better to explore than the other?

Should I stop in Interlaken or Luzern on the way to Zermatt?

Thanks

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