Grand Hyatt - FANTASTIC
We stayed at the Grand Hyatt 15-20 Nov and had the most amazing time. Check in was swift, we we're told which lifts to take to 26th floor (their are two sets due to the size of the place). 
When we got to our room it was immaculate, and I am fussy due to some nightmare holidays in the past, so I am hard to please. Spacious enough for 3 girls (and we had stuff everywhere!), bathroom was compact but modern clean and served its purpose.
Beds were comfy and room temp was perfect although air on did come on randomly without us putting it on. 
The hotel is situated in the perfect position, right next to Grand Central Station and the Chrysler Building, and is in walking distance for visiting all the sights with Times Square and Broadway which was only a 10 min walk away.
All the famous shops are close by too and Ground Zero is only a 10-15 min cab ride away....negotiate cab fares as the vary dramatically and the cab drivers are not shy in asking for a tip....in fact there quite rude...But that's just how they are in NY and it in no way spoilt the holiday in fact it's part of the experience.
Just around the corner is Bryant Park- I can't believe that no one mentions this place in any brochures as it was magical....ice skating and Christmas shops, food stalls and a really amazing atmosphere. It made our stay all the more special and it right on the doorstep! (Plus the public toilets at Bryant Park were immaculate- yeh I know it's not something to normally included but its rare and they were that clean it had to be said lol).
If you have never been before and want a great hotel in perfect location this is the place for you.....and the doorman Ray is the best.....