Passes: www.myswitzerland.com.
Where to go:- Once you've decided on your itinerary, book a train from Paris to Switzerland ASAP for cheapest price. They only get more expensive closer to the date.
Geneva = 1 day. Flower clock, IRCC museum, fountain.
Zurich = lots of money. It's OK, but it's nothing special.
Instead I'd hit the usual suspect - Bernese Oberland. Consider basing yourself in Grindelwald, Lauterbrunnen, Murren, Interlaken. Justification - very very scenic, very well set up for tourists, Interlaken's a major station so you can easily get in and out of the area, no car would be required. Itinerary whilst there - Schilthorn cable car lift (as seen in on her majesty's secret service), Jungfraujoch (don't go up if the weather's crap), boat trip on either thunersee or brienzersee (good when the weather's crap), trummelbach falls (major waterfall, at the end of the (relatively flat) valley from Lauterbrunnen, plus lots of walking trails which are as flat or as steep as you like.
You could also take scenic trains. Example: head to Montreux, take the golden pass train over to Interlaken. Bit slower than the intercities, but even more scenic.
That's just one region of Switzerland, there are others of course. See http://www.lonelyplanet.com/switzerland for more ideas.