Yup, Wangfujing is roughly a 20 minute walk to Tian. Sq and Forbidden City. There is a pretty awesome food court in the mall you should check out! This will take most of your one day.

If you goto the Great wall, that will take your second full day. Badaling is the more touristy/crowded area and easiest to get to via public transportation. You just take the metro to the North Station (Xizhmen??) and from there the train up to the Wall. You can take the bus back to save time.

If the weather is bad, you could use Summer Palace as a backup. Just metro directly to (Belgongmen??) and spend a whole day there.

Temple of Heaven is another choice, but that is smaller than Summer palace, closer to downtown and will not take a full day. Take metro to Tiantandongmen.