Hmm, plenty of restaurants, what would you like to eat? Duck? Western Chinese? Sichuanese? Shanghainese? Yunnanese? Standard Chinese?

A nice drink at Houhai sitting by the lake is an idea.

Duck at Liqun followed by a quick little hutong stroll in the surrounding area too (the area's under active destruction/renovation and has been so for over 2 years - but still, last I checked, had a pretty active life buzzing about).

Keep things simple and take a cab to and from the airport. You can get addresses at the airport, online or from this board if you ask. I'd leave actual sightseeing for another time.