Apart from every (well, nearly every) single classic, animated Disney film, my number one, all time Screaming Childhood Nostalgia film has to be TITANIC. From age 8 (with my mum covering my eyes over that smoochy, smoochy car scene) to this very day, I just can't get enough. And like you, as soon as I hear it, any part of it, my ears perk up, and I'm there (even my family know to call me if they see it on). I'm saying their lines with the characters, answering their questions (dramatically, of course). I really have to fight to contain myself when I'm watching it with someone else.
Ooh, and I, too, just watched princess diaries 1 & 2 for the first time in like 2 years around last month. LOVED IT.