Paris / Switzerland or river cruise

It's a 3 hour train ride to Geneva and 4 to Zurich. My preference would be to train it wherever I wanted to go and spend time exploring at the destination. You could also drive. Fly to Paris, pick up a rental at the airport, and drive it to your destination airport. Driving in a lot of Europe is quite picturesque.

To be fair, I am a huge cruise hater. I do not like others controlling my itinerary, and constantly being around people I can't escape from.

Don't be scared of driving, either. Once you get outside of the downtown of major metro areas, it's like driving in the US on interstates/US Highways for the most part. Different countries have different speeding enforcement mechanisms, and the gas station setup takes some getting used to. There are travel plazas spaced out (which you can get some food that's too good to come from a travel plaza), but there are not at least two gas stations every exit like there are in the US.

The train is a better option for most people, but it also depends on what you're planning to see in each city. If it's truly "in the city" you can use the metro or buses to get about anywhere. But, if you want to see stuff that is outside of the range of the metro, you might want to train it between both destinations, and rent a car from the airport if you need to. I always rent from an airport because it keeps you from dealing with urban traffic.

We did the Paris & The Heart Of Normandy Paris to Paris cruise on the Seine. Nice cruise but our favorite part was renting a car in Paris and driving back to Normandy. Based in Bayeaux and toured the region daily for a week. Best part of the trip!

Maybe 4 days in Paris, then high speed train to Zurich. From there you could go to Lucerne / Grindelwald or Zermatt and then return to Geneva to fly home. Switzerland is a beautiful country but one of the most expensive we have visited.