J’ai marché dans Central Park, traversé le pont de Brooklyn, et pris le ferry pour Staten Island pour apercevoir la Statue de la Liberté .

Nothing to be changed here, but a few comments still :
- Not sure capital letters are necessary in french, but provided those are American names, maybe they can or even should stay.
- "apercevoir" means something like "to (barely) have a glimpse". I have the feeling you used it well and on purpose here. I actually don't know anything about New York although this is my cousin's favourite city. I infer, the idea was to have a view on the statue during the ferry trip : "pour avoir la possibilité de voir la statue de la liberté pendant la traversée.", "pour avoir une vue sur la statue de la liberté depuis le bateau.", ...
- You have two "pour" following each others in that sentence. Both have different meanings but the meaning of the second one can be a bit tainted by that of the first one, not to mention the repetition that we usually try to avoid. You could eventually replace the first one with "à destination de" and or the second one with "afin de", "dans l'intention de".
- The style of the sentence (the use of "marcher" instead of something quieter like "se promener", a succession of coma separated short sentences with omission of the subject) gives a feel of a really busy and packed trip : "In one afternoon I went through this, this, this, and that : tick, tick, tick, tick.". Nothing wrong here, I just want you to be aware of that.
"Naturellement, j'ai visité les lieux les plus emblématiques de la ville : je me suis promenée dans central park, j'ai traversé le pont de Brooklyn, et j'ai même pris un ferry pour Staton Island histoire d'avoir la fameuse vue sur la statue de la liberté."
I think the répétition of "je" and "j'ai" as well as longer sentences with comments inside gives a better feel of time and emotional investment.

J’ai visité le Mmémorial du 11 septembre.

Your sentence is perfect, but you could connect it to the previous one, for instance with "aussi".
"J'ai aussi visité le mémorial du 11 septembre."

Malheureusement, 2,971 personnes ont malheureusement perdu leursa vies lors de l’attaque terroriste du S11 septembrer 11, 2001.

Starting the sentence with "Malheureusement" connects it as a consequence of the former sentence.
"Je suis allée sonner chez le pape ce matin. Malheureusement, il n'était pas chez lui."
"J'ai acheté une tartelette aux fraises pour l'anniversaire du chien du voisin. Malheureusement il est allergique aux fraises."

Furthermore "malheureusement" is a bit awkward here it rings like "unfortunate", which seems a tiny bit off in the context. I would suggest :
"J'y ai appris qu'en tout 2,971 personnes ont perdu la vie lors de l’attaque terroriste du 11 septembre 2001."
- Starting with "J'y ai appris..." allows to connect with the former sentence
- "en tout" allows to put an emphasis on the number
- In french we would say "ils ont perdu la vie", everybody losing its own I guess.
Nota : "perdre la vie" (to die) / "perdre sa vie" (to waste one's life) for instance, in my shitty work I can say that "je perds ma vie à la gagner" (a common pun : wasting one's life earning it)
- dates in french are microcosm to macrocosm : dd MM aaaa

Mon activité préférée était de voir les Rockettes au Radio City Music Hall.

If you went several times, like every evening, then your sentence is correct (imparfait => long and or regular activity).
If that was a one of : "Ce que j'ai préféré, ça a été de voir les ...", "L'activité que j'ai préféré a été de ... "

Le spectacle était spectaculaire.

Theoretically... You are 100% right... Now, formally we wouldn't qualify a noun with a related adjective.
I would recommend to change
- either the noun for instance with "Le show" (yes, we actually say that) or "La prestation"
- or the adjective with "fantastique", "impressionnant", "époustouflant", "incroyable"

J’ai marche me suis promené dans Central Park, j'ai traversé le pont de Brooklyn, et ai pris le ferry pour Staten Island pour apercevoir la Statue de la Liberté .

C’était ma deuxième visite à New York et j’espère que ça ne sera pas la dernière.