One of the things I love about symphonically based music is the reocurrence of important themes and motifs in a piece of music. As a percussionist in my local symphony orchestra, I have to say I'm quite familiar with the usage of this by the masters.
However, I also like rock and metal bands that utilize reocurring and familiar themes. This aspect of music is one that I find is consistently pulled off well by Dream Theater. As much as I don't see the greatness in their critically acclaimed album "Scenes from a Memory", they dabble familiar melodies in well all throughout it. They especially make great use of it in "Home", where they reuse chord progressions and drumkit rhythms from "Metropolis Pt. 1".
Another artist that I feel does this well is Nine Inch Nails. Anybody who has heard "The Downward Spiral" or "The Fragile" knows that several songs on each of those albums share a couple familiar melodies. Not only that, but Trent Reznor also writes in some great reocurring lyrics. If you've heard a fair amount of NIN material, chances are you've heard the phrase "Nothing can Stop Me Now" more than once, and not even just in one album.
Anyways, what are some artists that you feel use this technique well?