After about age two or three, I stop telling children how cute/adorable they are, and instead focus on other nice things to say ("You behaved so well at the restaurant!" or "That was so nice of you to share your ice cream with her!"), but I do enjoy making the comments to the parents ("She is too darn cute!" or "He's so handsome, you're going to have to change your phone number when he gets to high school").
It just feels so good to compliment a parent on their kid, no matter what it's about.