I pack more for short trips than I do for round-the-world excursions (see What to Pack: “Take 1/2 the Clothes, Twice the Money”). As part of my NYE trip to NYC, I did the same. While it was convenient to only have one bag, I learned a valuable lesson to expand upon the principle of packing half the clothes and twice the cash. Namely, bring a spillover bag for two reasons: 1) Purchasing souvenirs of any kind takes up space. 2) the perfectly packed suitcase becomes a pain to pack when jumping from one hotel to another, one country to another.
See all my Travel Lessons here.