transportation between Paris & Germany

Loretta, greetings. you may want to say WHERE you want to stay "near the Rhine" and in Switzerland and Italy. that way it will be easier to give answers as far as logistics and such. happy trails

By "Rhine" I assume you mean the scenic Rhine Gorge between Koblenz and Mainz.
Traveling by train is certainly the easiest way to go. There are two main high speed rail corridors to Germany. One, the Thalys train from Gare du Nord to Cologne, which is down stream from the gorge. The other, the TGV/DB route from Gare de L'Est to Mannheim, which is up stream from the gorge. So the route is 6 one way and a half dozen the other, which ever is less money and gets to where you want to go, and most convenient. From there it's an easy train journey up the Rhine valley to Switzerland then on to Italy.

You can catch a train in Paris and be in Frankfurt in less than 4 hours. From here, the Rhine is only about 45 min. away if you take the S-bahn to Mainz. Or, if your train stops at the Frankfurt airport first, get off here, then Mainz is just 30 min. away. From Mainz, head down the Rhine to your town of choice. When you are done with days of sightseeing on the Rhine, head back to Frankfurt and catch your train to Switzerland. Trains going to Zurich are fast and frequent. Just get your tickets 3 months out, for the cheapest prices.

Also, there's frequent high speed trains that run from that area of Germany all the way to Interlaken, via Karlsruhe, Basel and Bern (I think). I'm not sure where train originates from, but I know it stops in Mannheim.