Here are shots from my recent trip to New York city:
http://s108.photobucket.com/albums/n13/bdery/2008-06%20New%20York/Those were all shot with my Pentax K20D camera. Most central park shots were captured used the old Vivitar Series 1 70-210mm lens (and shows how great glass remains great through time). The Liberty Statue and night cityscapes were shot with a Pentax 50mm f2. The others were shot with the Sigma 17-70mm autofocus lens.
The 17mm of the Sigma (equivalent to 25,5mm in 25mm terms) was really useful in the city, where you don't always have the room to back up. Even so, I found it hard to isolate subjects most of the time... that city is much too crowded by people and buildings!
Enjoy! And feel free to comment.