all depends on your tastes.
i'm not a pizza 'connisseur' (spelling). most ppl who say patsy's (brooklyn) is good also say new haven pizza places blow it away...patsy's is thin, brick oven style pizza. i'm not a big fan of it.
there's a john's that's opened up in midtown (44thish and 8th) - if it's like their village counterpart, they only sell pies and not slices.
my personal faves are joe's (on bleecker/6th ave) and (something) ray's on 11th/6th. i didn't find 'great' places in midtown, but everyone's opinion is different.
for more food stuff, seriously, go to chowhound.com . and for other stuff near the expo...virgil's bar-b-q is good, there's little brazil on 46th st. (from 7th ave - 6th ave), the soup guy from seinfeld is open with huge lines on 56th and 9th (it is real good, but real expensive and there's nowhere to sit), a couple good thai places (pongsri and chanpen, 48th/8 and 51/9), a slew of 'world' places on 9th ave from 45-55. those are all places that aren't geared to large groups, however.
you might want to target one of the breweries for that..