The magic I do is strictly for my grandkids and their parents. I am not a professional by any means... They range from 3 year old to 21 year old. Two are in the 11-13 age bracket. This age is one where they still have many of the attributes of smaller kids, but they are beginning to question and look deeper into what you are doing, as their focus and ability to question things is coming out.
Many of my tricks are highly visual for the younger ones (Cups and Balls, Sponge Balls, Professors Nightmare, Cut and Restored Rope, Egg Bag, Needle in Balloon, etc..)
The 11-12 still really enjoy these type of tricks, but I add in Coin magic and Card magic as the younger kids cannot follow much of the card magic unless the cards have pictures) I also find the older kids love mentalism tricks, ...e.g. you read a card they select without touching it, Three-Way Test... As you mention the 'goofy guy' doesn't work as well, so I go to a very serious powerful Wizard, mode as I shift early on into Mentalism....kids at 11-13 eat this up.....maybe Harry Potter influenced much of this mindset in kids.....