Well, these four destination cities are not far from each other. The transportation between them is very convenient. I recommned the route: Shanghai - Nanjing - Suzhou - Hangzhou
1. by bullet train from Shanghai Railway Station to Nanjing Railway Station
2. by bullet train from Nanjing Railway Station to Suzhou Railway Station
3. by bullet train from Suzhou Railway Station to Hangzhou
Bullet train is faster than the ordinary train. If you don't want to take the train, you can take the bus at the long-distance bus station.