Occasionally I'll fall in love with a transition between two songs, and will use that pairing several times for several different mixes. For example, last year I made a series of substantially different mixes that had "Survive" by David Bowie and "Angels" by Robbie Williams as tracks number three and four, respectively, just because the transition seemed somehow perfect, and because those are two undeniably awesome songs that gave me some flexibility in choosing their surrounding tracks. (Maybe it's just me, but I feel that "Angels" is such a slamdunk of a song that it allows me to select something relatively obscure, weird, or downbeat as the followup. As Barry would say, it's very pussy of me.)