Grant Plaza is a very well located hotel, at the entrance of Chinatown, close to Union Square and all sorts of restaurants, bars and shops and lots of buses and metro stations.
Many key places can be reached on foot from Grant Plaza.
The place is quiet - the staff too - except for the traffic if you open the wondows. It is clean but do not expect any cleaning during your stay even if it is a hotel.
All in all, a nice place to stay at.