I have 2. First TTA, when we were little my mom loved it so we always HAD to ride. It was boring to me (especially as a teen), just sitting there riding around Tomorrowland. Now it's a not miss for our family. It's a nice break from the hustle and bustle of the rest of MK. We have even "stayed on" for a few cycles because DS can easliy relax on it and sometimes he really needs a break.
Second is IASW. Again as a kid my mom and grandmother LOVED it. Oh, that song, "please, no nana we don't want to." Again this has turned into a must every trip. It's partially sentimental, because my grandmother is no longer here, I now hear the song and immediately think of her. There is also something that draws kids to this attraction. DS loves to se the "kids" singing. I now even find myself singing it to my baby as a lullaby.