I'm traveling to New York City in August for a theatre trip and I have to choose between the Grand Hyatt or the Hilton. Which is closer to the theatre district? Which would you recommend?

Both hotels are approximately the same distance to most theaters. If you are going to spend most of the time on the West side the Hilton is a better choice; the East side, the Hyatt is the choice.

The Hilton is on 6th Ave., spanning 53rd to 54th Sts., while the Hyatt is at 42nd and Lexington. So, it depends on which theater you're going to as to which is closer to your destination.
Though both are in convenient locations, I find the Hilton a little more convenient. Of course, it depends on where else you're going while in NYC.

Don't stay at the Grand Hyatt. The bedrooms are just awful.

Nick, here are citysearch.com reviews of both hotels: Grand Hyatt http://newyork.citysearch.com/profile/7127704/ There are 3 Hiltons in NYC, here is a review of the one Howard mentioned http://newyork.citysearch.com/profile/11447014/ check them out and see which one you think would work best.