There is a metro station in the airport on the right as you head to the exit.
it is cheap and easy to use. Get a day pass. It is line 2 and heading to the city you have to change, I think it might be the first stop. You just walk across the platform and get the next train.
If you get out at east nanjing road it is a short walk to the bund where you can see the tall buildings across the river. The view is better at night when lit up.
nanjing road is a shopping street so plenty of food places. If you was alone I would say stay away from the offers of massage, it is risky... There