Plan on traveling to Munich by plane (spend 4 days), go by train to Interlaken (Murren-for 2 days), train to Montegufoni (in Tuscany-3 days), train to Cinque Terra (5 days), train to Florence, and leave for home. Any suggestions?
Rick Steves' "Best of Europe" will be really helpful to you in planning your trip. Most of the destinations that you mentioned are covered in that book including transportation connections, hotels, restaurants, and things to see.
Marta,
If this is your first trip to Europe, I'd also highly recommend reading Europe Through The Back Door as it provides LOTS of information on how to travel smartly and efficiently (hopefully avoiding problems).
Also, could you indicate whether you have to return to Munich for the flight home???
No Ken, we will be leave from Florence.