Last NYE my date and didn't know where we're gonna go, we'd just got back from Killington the same day. So, we ended up in a club... I was in tight leather-like pants and a sparkly top, date was wearing black pants and black sweater (!) and everyone else in the club was looking very festive...girls in fancy dresses etc. But it didn't matter, we had a great time. As for jeans...I wouldn't but that is up to you.. I'd say don't go to H&M if you want typical NYC - that's a Swedish chain you know... And their clothes are trash anyway. Fashionable and cheap, maybe, but trash IMO.