I always look at the hotel deal sites and then compare...usually you can cancel without penalty up to a certain point for most hotels, just read the print!
Hotels.com, expedia.ca, booking, etc.
Also try this, they are toll free, take all the info into account and then suggest hotels they work with:http://www.newyorkcityluxuryhotels.com/
I prefer to stay anywhere from central to upper east side, haven't really stayed elsewhere. Definitely do everything everyone mentioned if you can...visit the TKTS booth for cheap day of Broadway and off-Broadway tickets - I suggest the one down by the water - there's the Brooklyn Bridge and shopping down there as well, the lineups are way less than the booth in Times Square.
Go shopping!! Century 21 - they have one downtown but they recently opened a location in midtown!! Lots of cheaper brand names.
Go have dinner and dessert in Little Italy, on the way there in the Bowery area there's shopping as well.
If you walk around the Fashion district - and like purses - you can go into some stores selling cheap purses. Most of the shops don't do this as they're wholesale but you can find some that do and there are some great steals!
I'm going next month again and can't wait!!