The band re-entry and all of "The Pursuit of Truth" from Illumination Theory. Everything from the riff to the vocals/lyrics to the epic piano solos is just incredible. "Don't cross the crooked step" from Honor Thy Father, the intros to A Nightmare to Remember and The Shattered Fortress, all of Lost Not Forgotten, the ending of Outcry, the main riff from Systematic Chaos, and the "Bow down to Nafaryus" part of Three Days are good examples too.
And, it's a bit cheating, but "Razor's Edge" from Octavarium fits this in a "completely majestic" sort of way.