Hi Italia -
Welcome to the Forum.
With 8 days you would be better off using two bases. It will save some time on the trains, due to longer journeys if you have only one base.
A map and a timetable will be useful:
Here are some data on cities and regions you may wish to visit:
Luzern (German spelling; it is a German language region) is often considered a good base for first time visitors to Switzerland.
To see the Alps is not hard...they pop up on the horizon at a distance from many places. And, there are many Alps....the Bernina Alps, the Valais Alps, The Berner Oberland, even the Dolomites on the border with Italy. See attached image taken in the Emmental.
The most famous are probably those of the Bernese Oberland...the Eiger, the Jungfrau, Schilthorn, and others nearby:
You will be able to get close to them and and see a lot from the cog-rail train that runs from Lauterbrunnen upwards. It will be running.
In early December, the Winter season has not yet begun in the Alpine resorts, so many hotels will not be open and many cable cars will be shut down for maitemance or lack of customers untila approximately December 15th. Interlaken has few attractions on its own, but is a good base for the Jungfrau, especially in the off seasons, when more accomodation is available there.
Do you have any special interests beyond seeing the Alps? Hiking, skiing, cities, old towns, museums, train rides?
Are you from Italy?