On my last trip I bought the soundtrack to Illuminations / Tapestry of Dreams. I have never seen the Tapestry of Dreams parade but there is a recurring theme in the music that I recognized right away . . . but I cannot for the life of me figure out where I’ve heard it! Does Disney use this music in one of the parks (AK, maybe?) or in another show? This is literally going to keep me up all night, so if any of you experts have the answer, please do tell!
Skip to 3:40 in this video to hear the part that is driving me bonkers.
WHERE have I heard this before??? 
I’ve heard it too, and I also never seen tapestry of dreams. I think it’s been used in the end credits of a movie or a scene in a movie. Though which one I’m drawing a blank on.
maybe avatar?
One of the comments mention they play this at park closing, maybe that might also be it? You hear it as you are exiting.
Unless I’m sorely mistaken it’s one of the tracks they play at Epcot after Illuminations concludes. Whether it was written for that purpose or originated somewhere else I can’t say. Avatar and AK are reasonable inferences, but I don’t hear the theme in any of the Avatar soundtrack previews on iTunes and I don’t recall hearing it at AK. Also, once again unless my memory is failing me worse than usual, it’s use at Epcot predates Disney’s use/licensing of the Avatar IP.
I did see the parade, and it was one of the best that Disney has ever done. The music is still used in EP either before of after IllumiNations.
Thank you so much, everybody! I think you are right that they play the music after Illuminations ends, while everybody is exiting the park. I’m surprised I didn’t recognize it . . . but maybe I’m always too distracted by my aching feet to notice the music during that looong trek out of Epcot at the end of the day. 
So glad that mystery is solved! 