My favorites would be:
"Good Vibrations" by The Beach Boys - a three-and-a-half-minute "pocket symphony" that took six months to record, and its many melodic changes and complex vocal arrangements were worked out over 90 hours of tape.
"Heroes & Villains", "Cabinessence" and "Surf's Up" from Brian Wilson's SMILE - besides being elegantly structured musically, lyrically and sonically, the interesting thing is each of them is just a part of a bigger piece called "suite" or section, and SMILE is a unified long work in 3 sections (Americana, Cycle of Life, Elements) with a 4th short section comprised of "Our Prayer" into "Good Vibrations"as a coda. Freakin' genius!
"A Day In The Life" - no need to explain
Abbey Road Side 2 suite - of course