Early July is a good time to visit the Jungfrau region. Although the summer season begins in late June, some moderately high trails may not open until late June. The major crowds arrive in August, but July can also get quite busy.
as of yesterday, this special trail was not yet open -
Altitude is about 2300 meters to 2060 meters.
A standard itinerary would usually include some time at Luzern (about 1 hour from Basel by train after you reach the main station by shuttle bus from the airport) and time in the Bernese Oberland, especially the Jungfrau region.
There are refinements in those regions for various types of activities...hiking, scenic trains, museums, etc.
Here is one example of hiking and lake scenery from the southern part of lake Lucerne:
Take a look at the links above and consider two bases - Luzern and Interlaken - or, better, one of the alpine towns south of Interlaken, such as Wengen. (I like Wengen.) If you do them in that order, the train circuit makes sense. Interlaken is a good train connection base and a poor tourist destination for alpine scenery.
This map will give you the train routes if you zoom in far enough, so you can see where they run.
Under "points of Interest" in the menus, play with the entries under "traffic."
There are more detailed topo maps available if you are a hiker. Ask.
The timetable lets you know about all kinds of public transport.
Let s know what you think after you look over those links.
By the way - a really great itinerary takes 6-7 weeks, not 6-7 days. ;-)
So, if you don't like those ideas, spend some more time with: