Brought out son to his first game when he was 5 months old and would bring him to a couple of games a year for his first 3-4 years. He generally enjoyed the games, but if he got cranky, my wife, who didn't really care about football, would take him out to the concourse (this happened once, iirc).
As he got older, I'd bring him to maybe half the games, usually without his mom and he generally had a lot of fun. By the time he became a teenager, he was a lot less interested in football, so he'd go maybe once a season, which is what he still does, at age 21 (he's a senior at RU; he transferred to RU a year ago) - although now the attraction is the free booze and food, lol. He says he might want to come to a couple of games this year. His favorite memory (and mine, of course) was the Louisville game, when he was 12, and we stormed the field.