I don't really recall too much from when I was a kid, but I know that my son has tried every Christmas since he was 4.
When he was six he woke up when "Santa" came into his room to see if he was soundly sleeping. (We stage elaborate Santa escapades every year and video them). Santa said "Ooooopppsss!!!" and ran down the stairs and outside. Our son was beaming from ear to ear and we interviewed him. He said, "You see! I knew he was real and I caught him red-handed!"
Age seven, he designed a Santa trap in our new house. We had just moved in a week prior and Neth thought Santa would be thrown off by the layout. He slept through the night, but we have the pics and video to prove Santa was here. Even videotaped his dad and both uncles standing with Santa, so he knows it wasn't one of them just dressed up in a silly suit.
Age eight, another Santa trap, this one created with help from dad. They attached a string to the lightswitch in his room, which then attached to the door. When the door opened, the light came on. It worked, but was not enough to wake the sleeping prince. We got great video of Santa setting off the trap!
Age nine, Neth woke up when he heard us answer the door! He spied Santa out his window when Santa went back to his sleigh to bring in more presents. We reminded him that if Santa knew he was awake, there would be no presents for him. So he stayed in his room, under the blanket with the lights off. Got a great interview with him.
Now, age ten. Who knows what is in store! But we know he still believes as he just sent off a very funny and heartfelt letter to the Big Guy.
Kind of makes me wish he will stay a child always......