^ Also apologies if this was already discussed and just discount it and I won't make a fuss, but I wasn't sure if TSMS/TEC/TMW are acceptable. Far too tired to go back and check.
I can't speak for the PT and C&C songs, but I think Three Minute Warning qualifies, as it was only broken in to tracks for ease of moving through it. It was basically a one take jam.
The Sky Moves Sideways is like Pink Floyd's Crazy Diamond. One Song, divided into two parts, so it should count. Also, on the 2 cd version there is an alternate version combining the two parts into one big epic.
The problem I personally have with Three Minute Warning is not that it's divided into parts, but, that it is in fact a jam and not a composed song. For me an epic means that there is at least some arrangement and some thought on the composition and not just a long improvisation. But that's not for me to decide.
And here is my (not very innovative) list, sadly the minimum length eliminated a lot of my favorite longer songs.
1. Yes - Close To The Edge
2. Dream Theater - Octavarium
3. Extreme - Everything Under The Sun
4. Pink Floyd - Shine On You Crazy Diamond
5. Spock's Beard - The Great Nothing
6. Mike Oldfield - Tubular Bells (Part One)
7. Porcupine Tree - The Sky Moves Sideways
8. IQ - Harvest Of Souls
9. Transatlantic - Duel With The Devil
10. Neal Morse - Seeds Of Gold