New York City is not as dresssy as it used to be. You won't feel out of place dressing casually in most places tourists are likely to go. However, keep in mind that some high-end restaurants still require a jacket for men (more rarely jacket and tie), and people still dress up a tad more for the opera, ballet, and classical concerts. But New Yorkers are as likely to wear jeans to a Broadway show as the tourists, though the locals who might wear shorts during the day dress a bit more formally when they go out at night. Do bring a small folding umbrella; you'll need it for the occasional rain shower. You'll soon understand why New Yorker's wear darker colors, especially when you look at your rain-spattered pants after a shower. You'll be happier if you pack light; New York City hotel rooms are smaller than average, and if you need to wash a few things, coin laundries are widely available in the residential areas near where most hotels are located, including Times Square. And most New York City dry cleaners offer next-day service and offer reasonably priced wash-and-fold laundry service by the pound. If you have young children, pack a light-weight umbrella stroller; even kids who walk well may get tired.