France: Paris, Nice (Cannes and Monaco)
Italy: Roma, Venice, Florence
Spain: Barcelona
Austria: Vienna
Some Nice to see places:
France:All country:the western province to see chateaus, nortern
part to see Normandy and Moutain St. Michelle, southern part to
visit Cote d'Azur cities, all very beautiful places.
Italy: Milan
Germany: Munich and Berlin
Others: Amsterdam of Holland, etc.
Also, most small towns in Europe are worth to see
Here was one of my trip before:
Day 1: Arrival in Munich, Stay in Munich
Day 2: Munich
Day 3: take a tour to neuschwanstein, whole day. http://www.neuschwanstein.com/english/
Day 4: Munich - Salzburger, stay in Salzburger ( 4 hours train)
Day 5: Salzburger-Venice, stay in Venice (Mastre, a city close to Venice)
Day 6: Venice, Stay in Mastre
Day 7: Venice to Florence (4 hours train), visit Pisa, Stay in Florence
Day 8: Florence to Roma, 2 hours train, stay in Roma
Day 9: Roma
Day 10, Roma, take night train to Nice, France.
Day 11, Nice, Cannes or Monaco, stay in Nice
Day 12, Nice, night train to Paris
Day 13~17, Paris
Paris is the best city in the world I think so stay longer, at least 3 days.
If you still have time, take a tour to Chateau and Normandy in France. It's 3 days.
Have a nice trip