There are many ways to close your show. I know it may sound obvious but just do something good! The kids do not care what you close with, Cheers!

Been trying out Barry Mitchell cannon of doom. Send with a bang. Hoping to find a good smoke ext to also go with it

I use the dove pan baking routine with a foam birthday cake.

I've always used the bunny production in closing --bunny from hat, drawer box, rabbit pan or my favorite, the mail box.
With lots of patience and repetation, you can teach the bunny to entertain the kids--eg picking out a card from a deck that have Happy Birthday or a animal card that the birthday child selects.
Ricky

I do my bunny production/vanish/reappear routine but then I almost always close with the Magellan Levitation. Magellan is so good because you literally can do it anywhere and the kids don't have to even be far away for the illusion to look good or risk exposure.