As mentioned: this place - very talented wanna be Broadway stars sing and dance - pricey but fun for kids.
http://www.ellensstardustdiner.com/

You could check out the list of restaurants at Rockefeller Center. They have a Ted's Montana Grill if you want a family friendly chain. The American Girl store is nearby too.

OP again - thank you 13:38....I was looking for a usual suspect that might appeal to all and be fun for the kids first trip to NYC.

Uh, thanks PP, that was so helpful.

Is it so hard to assume that they probably will be good with a list of "usual suspects" for types of cuisine? New American, Italian, Bistro, Gastropub, Deli, CHinese, Mexican, etc? And offer a suggestion from there?

I'll start. If you want to do the really, really touristy thing with kids you could go to Stardust diner in the playground that is times square because the 50s themed staff sings and I think kids like that kind of thing

Need to be a little more specific about type of food and do you want close to Port Authority or Radio City? This is NYC we're talking about, not some highway exit where your only choices are McDonalds, KFC, and the snack section at the gas station.

Where should we have lunch before the show at Radio City? We're taking a bus into Port Authority. Two adults, two kids and a grandmother. Thanks!