The problem is, Manhattan is *so* huge, and there is really a lot of diversity between the various neighborhoods.  My thoughts so far are to stay over by Grand Central, but another service provider suggested something over on Park, near the Southeast corner of Central Park.  This isn't really a budgetary concern, but since this is my first trip, I would like to make sure it's a really good one, showing it merits a return trip.  
 
So, what are some opinions on where to stay to be the most conveniently located for guests to come visit me?  I guess taking into account things like parking (or public transit? Your trains are pretty efficient, I hear?), ease of travel to and from during the busy periods and lulls in the day [but from what I hear, there really never is a "down time" in Manhattan ] and possibly somewhere offering en-suite amenities like semi- to full kitchens? I have a decent gluten allergy, and tend to make a lot of my own dishes, since most restaurants seldom offer reasonably priced "boutique foods".  
 
Thanks in advance, gentlemen!  
 
-Cori

Thanks!  That was very helpful!