In this area there is a lot to see, the best thing if you have the time is to split it into 2 days: One to do from midtown up and another from midtown to the side of Madison Square Park. Since it is not only about visiting the typical places, but it is also good to walk around a bit, aimlessly, and get to know it even better.
For example, 5th Avenue and Park Av. are two very nice avenues to walk and go to the Uptown side and see the "elegant" part of Manhattan.
In any case, here is the complete tour so you can see everything you can find in the area:
If you take the N, R, Q subway line, it takes you perfectly to Union Square/14th Street station. When you leave, you will be in Union Square Park.
On 14th St. there are several places to shop such as: Forever 21, Strawberry, Failines Basement, and DSW for shoes. Also, along 5th Av. to 20th (and surroundings) there are many other stores (Anthropologie, H&M, Zara, Banana, etc). If the idea is to go shopping, we recommend going back one day specifically and walk this street from end to end!
If you walk down Park Avenue South to 20th Street and turn right you will arrive at Gramercy Park (it is the only private park in the city that only residents of the area can enter).
Going back on 21st street until you reach Broadway, turn towards 23rd street, you will be able to see the Flatiron Building. It is the famous building with a "flat" structure and triangular shape, one of the icons of this great city. This is where 5th Av. and Broadway Av. meet.
Right at the junction of these streets, in front of this building you will see Madison Square Park. Very close is the Met building that lights up in colors at night. And the gold-roofed building of the New York Life Insurance Company.
Diagonally to the Flatiron, you will find the EATALY market. This is a MUST. You can sit down to eat, buy something to take away, or just take a walk. It is an Italian market divided by sectors (pizza, pasta, bakery... it has about 7 restaurants and a market with infinite products), there is everything. If you want to sit and eat you have tables or you can also sit at the bar and order some snacks on the go.
And a good restaurant that offers korean/fusion: Atoboy.
If you continue walking along 5th Av. between 33rd and 34th streets you will see the Empire State Building (you can enter and go up to the terraces). You have to book a ticket first. The best time to go up is in the afternoon to see the sun set with the city in the background.
On 33rd Street and 6th Av. you'll find the Manhattan Mall, and on 34th and 6th Av. Macy's (remember to ask for the discount card at the Visitors Center that is on the mezzanine).
At 33 and 7th Av. is Madison Square Garden and next to it is Penn Station.
At 33rd Street and 8th Av. you will be able to see the General Post Office building.
At 40 and 8th Av. is the Port Authority Bus Terminal. And in front, the New York Times building.
Going up to 42nd Street before reaching 7th Av. you will see Madame Tussaud's Wax Museum.
Here you will have already arrived at Times Square (which goes from 6th Av. to 8th Av. and 42nd to 47th streets). In this famous intersection of avenues you'll find the Broadway theaters and all the illuminated billboards and screens that can be seen even better at night.
#GuestTravelTips: If your idea is to go see a Broadway show and you haven't gotten tickets yet: On 46th Street there is a booth that sells theater tickets at discounted prices "TKTS" (the tickets they sell are for the same day and you can get discounts of up to 50%). If you like Disney classics, The Lion King is a must.
Another stop that you can make if you are a sweets and candy lover is to go to the Hershey and M&M stores. They have a very original set up!
And for good coffee: IN COMMON orSIP & CO.
A few blocks away, you cannot miss the emblematic Rockefeller Center building. To go up to the Top of the Rock, you have to book a ticket. The best views of the city are always in the late afternoon.
At the intersection of 42 and 6th Av. you will find Bryant Park. From this park you will see the renowned black and gold building (American Standard Building) and next to it the Empire State Building which, due to an optical effect, appear to be together and be of the same height.
A few blocks from the park (3 approx), is the Grand Central Terminal. It's worth going! It is one of the most impressive stations in the world.
In addition, it has a hidden bar called The Campbell Apartment and an Oyster bar in the basement that is highly recommended.
Another secret to keep in your #GuestTravelTips: It has a hidden tennis court and you can reserve a time to play!
A few blocks away, at 42nd and Lexington, you can find one of the most beautiful buildings in NY, the Chrysler Building (here you can also go up and see a panoramic view of the city). If you continue on 42 to 1st Av. you will see the United Nations complex. There is also Virgin Records out there.
It seems like a lot, but everything is there in plain sight and very close to each other. In any case, since it is long from end to end, you can also split it and do it in two days to be able to enjoy it better and not miss anything.
A great recommendation if you are in the area, end the day at 230 fifth Rooftop Garden. One of the most beautiful rooftops in all of NYC. Full of plants and with a great view of the city, appreciating the Empire State in the background, it's amazing! Ideally arrive towards evening/night, to see the sunset and then the whole city illuminated.