Hi Happy,
Basically, it's more worth it to take a package tour to Shanghai. Coz' they'll bring you to the towns which are nearby like Suzhou, Hangzhou, Nanjing and Wuxi. If you were to come free & easy, paying to go to these other places can be quite costly coz' you gotta rent a car and a driver and gotta seperately settle accomodation there.
Besides, going on a package, you will have a coach to take you around Shanghai. The traffic situation can be rather bad here thus if you take a taxi, you might end up spending a lot. The subway and public buses are decent but takes a bit of understanding to move around.
These days, these tour groups, they're very experienced and know where are the places to go eat and shop, so it's quite worth the money. I live in Shanghai so if you wanna know about the city or planning to take a trip here, just feel free to ask me questions.