Why New York?

In both Catcher in the Rye and The Bell Jar, most of their plots take place in New York City. Coincidence? I think not!
During the 1950s, New York City had the largest population in the world, rising to prominence after WWII. This led to a massive economic and cultural boom, leading to new opportunities for aspiring artists, like Salinger and Plath. As both had lived in New York, they could have found the experience of living in New York impactful enough to place their characters in that setting.
 Placing their protagonists in the hustle and bustle of NYC also helps to highlight the loneliness the protagonists go through. Being alone is bad enough, but the feeling of being alone in such a massive and busy city is so much worse. Additionally, the relative proximity of different and iconic settings makes more of an impact to the reader-- Holden critiquing the Radio City Music Hall catches the reader more than him just critiquing another dance show without the context of cultural impact Radio City has made.
Or, the books could be set in NYC because Salinger was born in NYC, and lived there until he was sent off to boarding school; and The Bell Jar appears to be based off of the experiences Plath had when she went to work for Mademoiselle magazine in NYC for a month..

Daedalus or Icarus?

In Portrait of the Artist as a Young Man, our protagonist Stephan Dedalus often compares himself to his namesake-- the Daedalus of Greek mythology. However, I feel like Stephan is more similar to Daedalus's son, Icarus.
The Daedalus of Greek myth was a skilled inventor who built the Labyrinth of Crete for King Minos to house the monstrous Minotaur. Once he had completed his work on the Labyrinth, Minos trapped Daedalus and his son, Icarus, inside. To escape, Daedalus fashioned both him and his son a pair of wings to fly out of the Labyrinth. However, Icarus's hubris got the better of him, and he flew too close to the sun, causing the bindings on his wings to melt. Icarus's wings fell apart and he fell to his death into the Icarian Sea.
What we see of Stephan's character throughout the story seems closer to Icarus's character than Daedalus's. Stephan is often prideful, demonstrated in his disdain for human interaction or companionship, during the early chapters. Icarus's mortal sin was pride as well, linking Dedalus more to Stephan than Daedalus.
Stephan aspires to be like Daedalus, wishing "to create proudly out of the freedom and power of his soul, as the great artificer whose name he bore". This kind of put Daedalus on a whole other playing field, similar to how a son would look up to his father or something (hint hint). 

Interestingly,  Stephan never mentions either Daedalus or Icarus by name. Icarus is never alluded to, while Daedalus is alluded to 3 times as the "great artificer". I think Stephan doesn't even want to think about the possibility that he could be closer to Icarus than Daedalus.