First of all, thank you so much for Lucas and Gunzel for your helpful informative reply.
I really believe that public transportation in Switzerland is one of the best public transportations in the world.
However, i should be clearer about my trip. Well, i will travel with a group of 3 people, my parents and I with 3 luggages. Hope you can image dragging big 3 luggages around towns during our trip. That's not an ideal plan for me because my trip is a multi-cities trip where we stop by some cities or some tourist spots just a half day or a several hours..not stay over night so if we travel by public transportation, there is no place to left our luggages, so.. it means that i have to carry the luggages around town which is really inconvenient. I'll give you an example of my itinerary.
1st day: Will be landed in Geneva at night so we will stay over night and in the morning, we'll get the rented car and leave Geneva right away to Lausanne, travel around Lausanne and stay over night there. So first day, we'll park the car at the hotel's parking.
2nd day: Leave Lausanne and my destination is actually Bern, but we will drive pass Vevey during the route to Bern, so I plan to stop by Vevey and just have a short visit in Vevey (like a several hours) and in the late afternoon, we head to Bern and stay over night there (park at the hotel)
3rd day: Leave Bern to Interlaken. But as it is just about 60 km away from Bern to Interkan. So I have a plenty of time left, so I plan to visit Brienz lake before we go to Interlaken.
4th - 6th : Stay at Interlaken for 3 nights (including plan to visit Jungfraujoch, Grindelwald, Lauterbrunnen, Stabbach Falls, etc.) and so, of course, we will stay at a hotel which provides car park. But as we already rent a car, so that's why I ask for any recommendations for the places where I can drive to (I prefer driving rather than using public transportation **If possible** because I already rent a car...
According to my plan above, you'll see that i shortly stop by many places and continue to other places. So dragging luggages while travelling is not a good idea. So I really do hope you guys understand my situations and plans.. so please do help suggest or advise for places in Interlaken or nearby where I can drive to.. such as nearby countryside areas around Interlaken which is not a "car free zone" and I can drive to with no or less strict parking rules. And for the places in the downtown of Interlaken, I will not drive for sure, I will leave the car at the hotel and enjoy walking around town and/or use public transportation if needed :D that's some of my plan.
So anyone would give any further information or suggestions would be really appreciated.