My sister is going to be 30... If we don't stop and see Pluto and Mickey, she'll throw a tantrum like she's 5.
It's all part of the magic. We love to take a family photo with Pluto, and I love seeing Buzz. He was my favorite childhood "super hero" and I still love seeing him.
My friend went to Disney for her first time last year with her aunt, uncle and 16 yo cousin. She kept telling me that she wanted to get the Mickey ears and take pictures with characters. The 16 yo cousin told her she was too old (also ~30.) My answer: Once you enter the park, everyone is the same age.
Now, there was a time when we were waiting in line and some guy with a backpack and a Duffy toy hopped into line. He was loud and very over the top. When he went up to meet with Chip and Dale, he was posing and joking with them and handed them lollipops. THAT was a little weird. You could see parents grabbing their kids hands. Obviously it's wrong to judge... but this guy was a little strange.