I used to travel to NYC a lot for work, from Europe. I didn't need to pack a suit. I usually packed a change of underwear and a t-shirt, and laptop etc in my cabin bag. I usually bought some jeans and a few clothes which were cheaper, like brand jeans, etc. Some toiletries (the small travel sizes) when not provided by the hotel. Then I would go to Canal and buy the cheapest bag for the return.