Advice on June Switzerland itinerary please

I'll make this short...14 night trip, want to stay at least 3 nights in any one hotel. No car - all trains and buses. * Fly into Zurich, head to Lucerne * then Interlaken area * then Zermatt * then Lake Como/Lugano area (4 nights) * back to Zurich

Are we missing anything in St. Moritz that we can't get elsewhere? Is Zermatt and Matterhorn really worth 3 nights?

Thank you for any help!