Hi Tibor,
Anna's suggestion for the Times Square Area is very good. I would also suggest that once you are there walk over west to where all the Broadway theaters are at about 7- 7:30 PM and you should have lights, and people gathered to go into the shows.
For me the best street photos would be in the East Village. To have some light...my suggestion is to go to St. Marks' Place (8th St.) on Stand on the corner of 2nd Avenue where they cross. Of course walking up and down St. Marks Place is good too. It is lit up and has very interesting looking people. The shops are unusual...as are the people. Ask anyone where St. Marks Place is. :) Right on the corner there ( if it is still there) is a place called Gem Spa....It is quite famous...and you want to go in and have a Vanilla Egg Cream. It is a NYC soda..special...Lou Reed sang about them. :)
Another interesting place in terms of colorful people, would be Hell's Kitchen ...lets say walk along ninth avenue - start at 35th Street and walk uptown (North)...until about 50th St...or even on 10th Avenue...
For a Cityscape...there was a place called the Beekman Tower..on lst avenue and About 49th St. You can google it for photos..It may not be open but it is worth checking...because there is a rooftop lounge (enclosed) which has a view of Manhattan that is spectacular. Most people had never heard of it. I lived closed by and that is how I found it. If you find a table on the West side.you can see clear al the way down lst Ave...and all across Manhattan. You will have a view of the Empire State...and all the important buildings..right in front of you. It does seem like perhaps it has changed to an Apartment complex but it might still have the rooftop lounge...It is worth a call. Also, if it is still there ...what is good is that you will not have the typical view most people have when taking photos. Bring a circular polarizer if you are concerned about shooting through glass...
In future - since you probably already have your hotel...if you want spectacular views...go to the UN Plaza Hotel. I have stayed there a number of times when I lived in NYC. the Windows are celing to floor and you can take amazing pictures...just ask for a room facing South West.....or West...
http://www.millenniumhotels.com/usa/oneunnewyork/accommodation/deluxe-room.html
Have a good journey.
Phyllis