There are also local travel centers that can be a huge help when you arrive in a place last minute. When I had to do some New York travel at the last minute I just stopped by a travel information kiosk at LaGuardia and didn't have a problem putting together some plans. They even booked a nice hotel for me that stuck to my budget.
I think too many people stress about getting everything perfect on their trips and tend to get caught up getting everything set in stone in advance. I actually found out about some smaller events I didn't know were happening in the city just by asking when I was there. Nothing like the knowledge of the locals.