Like the post #7 mentioned, I think Lengel narrating the story in his point of view will be quite interesting. Lengel, unlike Sammy in the story, is a fully grown adult who needs to take the responsiblity of holding up a family togehter. For him, the job at A&P is a full-time career and a way of supporting his family whereas for Sammy it is just a part-time job that his mom got for him. Such contrast in age and role in the society will be quite interesting to observe.

All the suggestions already made are interesting and helpful. It might also be interesting to hear how Lengel would tell the story, just as it might also be interesting to hear the story told from the perspective of Stokesie. Both of these males hold positions of greater responsibility than Sammy does, and thus both of them might be able to offer intriguing (and perhaps more mature) perspectives on Sammy's behavior than Sammy himself is able to offer.  Although Sammy clearly sees Lengel as the villain of the piece, Updike offers evidence to suggest that Sammy's perspective is narrow and perhaps at least partially flawed.

It would indeed be interesting to hear Queenie tell the story (There was this guy in a store, and I was in my bathing suit .... Well ...), although it would then include a different backstory that would be less relevant to the thematic intent of "A&P." Perhaps if the store manager narrated as an objective observer, he might attain the overall thematic import as he could tell the backstory as well, since he is a friend of the family.

I'm thinking along the lines of Post 3.  I imagine Queenie telling the story.  I can imagine her going through the aisles thinking that Sammy is checking her out.  I can imagine the tension being within her as she decides whether he is a loser or not.  I could also imagine tension within herself as she decides whether she has done the right thing by coming in to the store dressed that way.  Either way, there could be dramatic conflict and I think that the story could still be interesting.

It's hard to argue with the points made in the previous (and superb) post, but I think the story as told by Queenie would be an interesting one--provided that she did actually notice all of the attention she was receiving from Sammy. It would come from an entirely different point of view: still juvenile, but from a female perspective that could be just as enthralling as Sammy's. Whether she recognized his actions as gallant or stupid--or both--would have still made for a good tale, especially in the hands of Flannery O'Connor.

With the point of view in Updike's "A & P" being that of Sammy, there is the vantage point of a young adult viewing his world with a certain cynicism. For, he sneers at the "sheep" and the "house slaves," the shoppers who "...knock against each other, like scared pigs in a chute" when Sammy tells Lengel that he quits. Furthermore, he is very critical of those in authority, such as Lengel, finding him too impressed with his managerial position.  For instance when Lengel repeats to Queenie "this isn't the beach" after she explains that her mother sent her for a jar of herring snacks, Sammy ridicules him,

His repeating this struck me as funny, as if it had just occurred to him and he had been thinking all these years the A&P was a great big dune and he was the head lifeguard. 

Sammy's action of quitting in order to display heroic behavior to the girls--an act of chivalry, as it were--is uniquely the act of a young man who tries to impress the girl he finds attractive.  Indeed, it is an impulsive act, and afterwards Sammy has a clear insight into it, realizing he is now in a limbo between two worlds, that of the adult and that of the youth.

So, if Updike's story were to have a different narrator, the perception of the situation and of the other characters would surely be greatly altered.  For example, if Lengel were the narrator, the story would lack internal conflict as Lengel would simply see the girls and view them flatly as offensive without any romanticizing of them. And, the conflict between him and Sammy would be less dramatic as he would not be affected in the same way as Sammy who is on the outside of the world of the A & P, realizing the cost of his chivalric act.

If a customer or another employee such as Stokesie were the narrator, there would be no dramatic conflict as these people are flat characters who undergo no change, and the narrative would be banal and pointless. Likewise, if Queenie were the narrator there would be no character change or dramatic conflict either, although the youthful cynicism could be a motif.  Clearly, for the development of John Updike's themes of Choice and Consequences and Indiidualism there can be no other narrator but Sammy.