I live in NYC, and go to all kinds of restaurants on a regular basis (even some of them-thar high-falutin' ones ). I am also rather on the petite side, and am, well, not able to finish a meal, usually. It's been my experience that waitstaff will ask if the meal was to my liking, and when I reply that it was good, and that it was simply too much, they ask whether they should wrap up the remainder for me. I don't think to accept is rude at all, and I am neither too proud nor too rich to refuse a meal of good leftovers the following day.