There is quite a bit to ask Nick Carraway, as he leaves a lot of information out of his narrative.

A question that pops into my mind is one that critics have posed: Nick talks near the end of the novel about an obscenity written on the steps of Gatsby's house at the time of Gatsby's death. Nick rubs it out with his foot, but we never learn what it says. In a letter, I would ask what the obscenity was, why Nick thought it was written, and if it seemed to speak to any truth about Gatsby.

Ellipses (". . .") are a punctuation mark that indicate that something has been left out of the narration. These also raise curiosity, as they occur frequently in the narrative. Much has been made of Nick riding the elevator with Mr. McKee and ending up in his hotel room. I would ask Nick what went between the elevator ride and the following ellipses:

. . . I was standing beside his bed and he was sitting up between the sheets, clad in his underwear, with a great portfolio in his hands.

What exactly was going on with Mr. McKee? Why does such a small character enter into the narration at all? More to the point: is Nick communicating to us that he is gay? He couldn't say this outright in the 1920s, but he could today. I would also ask if Nick believes or knows Jordan was gay and was simply using him as a cover story.

I am also curious about what happened with the girl back home in Chicago: we never do get any definitive closure on that episode. Nick says he needs to break up with her: does this happen? What happens?

Putting myself in Gatsby's shoes, I can think of quite a few. I will offer a few and then give possible answers/directions to the questions.
1. According to Nick’s quote, “They are a rotten crowd…You're worth the whole damn bunch put together."
What makes this crowd so "rotten"? (It is their carelessness...that is what separates Gatsby from the likes of Daisy. Refer to the conversation between Nick and Jordan when she is driving.)
-What makes Gatsby “worth the whole damn bunch” according to Nick? (Gatsby is not so careless. He feels, wants, and dreams at a level they are not capable of.)
-How did Gatsby turn out all right in the end? (He dared to dream and to never let go of those dreams. He, like the American Dream, saw no limit to potential and he reached for it.)

Wow - what a great letter this could be. Nick was the only person (other than Daisy, eventually) that was privy to most of Gatsby's life. He was also lucky enough to know Daisy and Tom before any Gatsby interference. Some things that I would like to know from Nick:

What noticeable changes were there in Daisy after she learned that Gatsby was close by?
What were his real feelings concerned the rumors floating around about Gatsby?
If he would have had an opportunity to speak to all of those people that didn't come to the funeral, what would he say?
What if he had the chance to speak at Gatsby's funeral?
Why didn't he think it was worth while to attempt to make a relationship with Jordan work out?
What does Nick believe was the reason he was so easily corrupted in an area where everyone else around him was?

And on and on...this could go in 100 different directions. I'm sure there are other posters who would be willing to fill in some more gaps!