Of course I put things away as I work, and there is no way for the kids to get to inspect my props, but that doesn't stop them from coming up to me after the show to thank me for entertaining them, and kinda take a look around. These are facts that are common to all kids magicians, but I have never had a room full of kids at a party just sit there after the show like gentlemen, and ladies, waiting for permission to get out of their seats, and if that ever happen to me I would have to add some excitment to the ending of my show. You can't expect kids at a party to act like they are in church.

Then there are the times when the "autograph" line starts.

Though there is no perfect solution that fits every audience, it is how we react to this an every situation that can tell a lot about a person and performer.

Another "solution" I have is telling the kids that after I clean up they can get a closer look at some of the puppets. I have 2nd string spring animals and such.

As said wisely above kids will be kids...

At the end of a birthday party show, I hand out souvenirs and the lid of the prop case is in place. There's nothing to see.

For larger shows, the kids are typically wrangled by the teachers or volunteers, so they don't get a chance to look into the case.

Good point Starrpower.

It's very important to keep the kids constantly entertained AND organized.

Kids respond very well to competition, and earning things through specific good behavior.
For example... I am going to float a kid in the air who is sitting cross legged, and smiling, with one hand in the air, etc...