I have had an amazing experience with an intro but cannot point to it or let anyone hear it unfortunately but I can at least talk about it. It was in a live Glenn Campbell concert. He came to Australia quite a few years ago and brought a stellar band and a small orchestra as well.
It was the intro to Wichita Lineman. It lasted at least 10 minutes and I am not joking. It was hard to tell what the song was or where it was going to go but it was just amazing. They eased into it and Glenn did like a long guitar solo, all this before he even sang. But somehow they managed to ease into the progression just as it was about to start and it was like magic. The very second you figured out what was about to happen he sang the first line...
I am a lineman for the county.... This is a beautiful song and it has a deep emotional effect on me. When I hear it now it still has that effect. If you look at any Youtube videos of him playing live he does not do the long intro so it is hard to find if at all but it happened at this concert though. I will never forget it. Seeing Glenn live was one of the highlights of any live gig I have ever heard and I have heard a few good ones that is for sure.