Check out Fodor's for midtown west- there are two GREAT delis, Carnegie and - crap, i can't remember the name of the other one, but it's up one block and it's not listed on that. I'll let you know if I can think of it. Okay, that's not the *healthiest* option, the sandwiches are enormous and delicious.. drool.. oy. The site has a price approximation which is pretty helpful. If you're downtown at all, check out a cute little vegetarian place called Red Bamboo: http://www.redbamboo-nyc.com/
. Hotel staff, in my experience, is pretty knowledgeable about restaurant options.
As for snacks, I'd try luna bars, a few crackers with peanut butter, carrot/celery sticks, pretzels.. things in that variety.
Have a good trip!