Which places in Switzerland to visit and the best way to go to Venice from Switzerland?

Me and my wife went to a trip to Europe last year that included Paris (5 nights), Amsterdam (2 nights), Prague (3 nights), Rome (5 nights) and Florence (2 nights).

Now we are going on a trip with my brother and his wife this year and thinking of going to Amsterdam (3 nights), Paris (2 nights), Strasbourg (1 night), Interlaken (2 night), Venice (2 nights), Florence (3 nights), and Rome (2 nights).

Everything looks perfect minus the Switzerland part. We want to spend 2-3 nights in Switzerland but I have no idea about where to start. We like big and happening cities usually so not sure if we’d even enjoy Switzerland but don’t want to skip it this time.

Where should we go? And should we rather fly to Venice from somewhere instead of a 7-8 hour train?