You can go to visit West Lake, Hangzhou Botanical Garden , Thousand Islets Lake (Qian Dao Lake) and Xitang. All of them are worth eyeview from elderly and children, I think.
You can rent a car at the Long Distance Bus Stations in Hangzhou; most of them offer car renting service. There are also many car renting companies in Hangzhou, the price is about CNY350–CNY1600 per day with a driver.