for New York, if you're staying for like 2-3 days, you can do some tourist things...
bway shows..... the famous ones... like phantom, les Mes, or lion king...
or off bways...... like blue man group, or stomp are pretty fun...
do some shopping / or window shopping on 5th ave.... if you're from the suburbs...
window shopping on 5th ave for a few hours on all the big stores would be cool....
(that's if ur lady doesn't go completely nuts....)
visit empire state building.... (well... not that impressive... but its a tourist thing...)
if you have not seen avatar, then go to lincoln square IMAX theater to watch it...
depends on what you're into, if you're into music / jazz, you can try some jazz clubs at night,
or comedy clubs...
or if you're willing to spend, pick a signature restaurant, and have a dinner there...
of course there are a lot of museums.....
as a guy, I personally like natural history....
(I can easily spend a day there...)
but a lot of ppl like Metropolitan also.... and there are tons more....