Have to agree with TDC Nala...thank you to the OP for being somewhat concerned. While I completely understand that you are going to find children everywhere at WDW, that doesn't mean that everyone should be subjected to screaming children when eating. And I don't particularly care if it's Cosmic Rays or Flying Fish! My kids had expectations when eating out..they were expected to have certain manners. Babies are different though..they can't be expected to have 'manners'. But, their parents can. If a baby gets grumpy and starts screaming, I always appreciate it when a parent takes the child out and tries to calm them before returning. While I understand that you aren't going to see any of those people again, do you really want to sit there, with a screaming child, trying to have an enjoyable (and expensive) meal??? And I'm not even thinking about those around you!!!
So...should you be concerned with what others are feeling? Yes, but only to a point. Let me share a story with you.....a friend and I were eating at Tuttu a few years ago. There was a youngster who was really acting out...yelling, screaming, just making everyone around that table miserable. And the parents didn't seem to be doing anythng about it...just kept talking and eating. Others in the area were staring at that table, and making faces, and comments amongst themselves. Well...long story short....my friend posted that incident as part of her trip report, in not very glowing terms. Is seems that the mother is a DISer...and took exception to what was posted about her child. Now...nothing was said that was a lie, or an exageration..only what everyone saw. But, that mother was not a happy camper..she let everyone know that her child has 'issues' and they deal with it as they see fit..and didn't really appreciate seeing her family being discussed in an open forum!! Oh, it was a wee bit uncomfortable.
But. my point is this....yes, that child may have had 'issues',and that family had every right to eat wherever they chose to. But, they needed to understand that their child's actions impacted other's dining experiences that night. Those other people had also paid for their meals and had every right to expect to be able to carry on a conversation without having to yell over a screaming child in order to be heard.
So.....feel free to head to any of those signature meals. We ate at Flying Fish in August and there were plenty of families there. The kids were all nicely behaved and no one had any reason for complaint. I'll be eating at several signature dining spots in Dec...I expect to see kids there, of all ages.