Mentioning Jungfrau sounds like that's one of your destinations.
I'd recommend Schilthorn's Piz Gloria as my prefered mountain destination.

It's cheaper if you don't mind Cable Cars and has 360 degree panoramic view of the Alps (from world's first revolving resturant featured in the James Bond film On Her Majesty's Secret Service) whereas Jungfraujoch doesn't have such breathtaking panoramic views.

It's travelable from Lauterbrunnen if you stay there (previous post).

www.youtube.com/watch?v=eOVlshrGUxM

Murren is also a nice stop en-route which has pretty Apline meadows there to see en-route.

If you go to Jungraujoch, get off at the second to last stop while it waits a few minutes and go to the moutaineers exit door where you go through a cage with warnings that only experienced mountaineers should use (as no rescue is available beyond). Open the door to the mountain and the experience is like looking into the gates of hell; pitchblackness and wind sucking you from the door! Hold tight.

HBF