Oh, my, there's so many!
For sure, "When You Wish Upon a Star" - especially if it's being sung by the Dapper Dans... never fails, I always get goosebumps!
Also, almost anything the Dappers sing will do the trick, to be honest. Along with Scoop and "I Wanna Be Like You" (which he sang to Bonnie & Kellie when we first met him, 'way back in 2002! Can't believe it's been that long!)
"Wishes" - oh, man, I just go crazy over that one, too...
But probably the main thing, on our first day of any visit, when we step out onto the street from under the train station at the Magic Kingdom... and I hear that background music playing for Main Street USA... I really get into a magical mood!