You, sir, will be drowned in a pool of music.
Starting off with early Hardcore, first that popped up in my mind.
'Like it, dislike it.
But I'm sure that's not exactly what you had in mind
Then there's Octavarium by Dream Theater which takes 24 mins total and builds up slowly, as you described.
But which is, I think, also not exactly what you had in mind.
Then there's alot of guitar solo's that build up tension, for example:
Animate-Inanimate by John Petrucci
And the all epic:
For the Love of God by Steve Vai.
Alot of (Psy) Trance/ Techno have slow starters, intro's from other songs.
Too bad there's few good Trance/ techno songs on Youtube or my Pc at all
There's Venetian Snares tho, which has Szamar Madar and Hajnal which starts off slowly but that's Breakcore, rather then Trance / techno.
Looking at the Classic Rock genre you should take a look at:
Pink Floyd - The Wall
And:
White Rabbit by Jefferson Airplane - Acid rock, but classic nonetheless.
Or maybe Into the Void by Black Sabbath.
Also have to throw in Jimi Hendrix, as an act of respect - try Machinegun :3
I'm not really that into the Blues, but my parents where so I kind of grew up with it, there's only one song I can remember to build up slowly being Hurt by Johnny Cash.
Random other suggestions are Fell on Black Days by Soundgarden.
Dopesmoker by Sleep (1:30 hr Stoner Doom Metal songs ftw.)
Under the Bridge by RHOP.
This Godless Endaevor by Nevermore.
I may not have helped you at all with this post - but you could of been more specific
If you'd be more specific, I could try to open my 125 gig music map and look some up for ye
