First trip to Swizerland

Hello, We ( 9 adults) are planning a trip to Switzerland in May 2013 for 6 days and itinerary is as below:

day 1 - Land Zurich 10:15 am , rent 2 cars at the airport
- Rhine Falls
- sightseeing in Lucerne
- check in to a hotel in Meggen

day 2 – drive to Weggis(park car)
- Rigi
- return back to Meggen
(Can we mix another short excursion on this day?)

day 3- drive to Lucerne(park car)
- Golden Roud Trip to Pilatus
- return back to Meggen

day 4- drive to Grindelwald(park car)
- Head for First / Mannlichen (do some hiking)
- check in to a hotel in Wilderswil

day 5- drive to Stechelberg(park car)
-Schilthorn/Mürren (do some hiking)
- return back to Wilderswil
(Can we mix another short excursion on this day?)

Day6- drive to Vevey sightseeing
- onward to Lavaux Vineyard
- travel on to Geneva
-check in to a hotel in Geneva

Please let me know whether it is necessary to get a Swiss Half Fare Card or a Swiss Flexi Pass?
Should any suggestion to improve the itinerary will be much appreciated.

Thanks in advance.