- Hotels. I feel this is one of the least explored location for ghosts. Many people wander through there, there are bound to be stories attached.
- Old cities. New York is teeeeeeeeming with activity, you just need to keep your eyes open.
- Anywhere near water. In nearly all my cases, there was a body of water nearby. We're not sure what attracts (or traps) ghosts to water but it's worth looking into.
- Forests. Now, I'm not suggesting going into the woods and sitting in the dark all night waiting for ghosts but where do you think all those campfire stories came from... ;)
- Theaters. There are many accounts of hauntings, both residual and intelligent, at theaters. Perhaps the energy that embodied the actors just don't know when to give up their 15 minutes of fame...
- Schools. Lots of energy here, colleges especially seem to attract ghosts. Check the dorms and older buildings for activity.
You may have noticed that I didn't include cemeteries, there's a great reason for this. THEY'RE ALL DEAD. By the time the body gets there, the spirit has already either attached itself to a location or it's moved on to wherever it's going.