Not sure if this belongs here, or might belong in 'Music and Musicians Exchange' , but here we go. 

So if things like the Whirlwind are suites, would it just depend on what you say it is? 

Wondering for a future project, 

Frets N' Worries

I'm not sure what I will say is gonna help ... but I'll try.

Go listen to the greatest symphonies ever written in the history of music. Stop thinking of it all as just a rock song, which is a problem ... since most folks don't really know how to "evolve" the music into something bigger and possibly better. Instead, they change the beat or adda "bridge" and then go somewhere else, and of course, here comes the guitar ... Funny how orchestras for hundreds of years never had a guitar and no one missed it ... and now, we don't even know how to listen to things without it!

Rock music, in general, has not exactly "grown up" from its basics, and the idea/fact that the main setup is still the same 70 years later, should tell you that along the way we have lost the ability to CREATE and DESIGN something different and new ... we always "default" to the same thing, process, and above all ... the worst ... a format!

If you want to extend something, and create a long piece, you have to tell any "format" to take a hike ... but I'll tell you that 9 out of 10 fans, even here, don't like that because all they are listening for is ... you gotta it ... the stuff they know and feel comfortable with ... think about Debussy and Stravinsky and many others that were not originally "appreciated" ... and today, we love them dearly. Which tells you all you need to know about an audience. 

If you want something longer, allow your imagination to move on and along ... don't stop for a bridge or a guitar or a (heaven forbid!) a drum solo. Forget the "solo" ... concentrate on the "full" experience of the music ... go look at the score sheets for many operas and symphonies and realize how so many instruments can come together and how 3 of them (and a cheap drummer) really ... sound like crap by comparison, not even discussing the composing elements within it.

Look up exercises in music for IMPROVISATION, so you can learn to "extend" your inner sight for music ... right now, I think you can only see a pop song (so to speak!).

If you have 33 hours on your hands, check out 'The Rise and Fall of Bossovania by PC III, that's how to extend a piece to untold limits. (if untold was 33 hours, that's about 2 1/2 the Veatles catalouge) I've written the lyrics, it's just musically it could be tricky. Improv is something i've been experimenting with for a while, and i've been getting better at improv, in a sense

Lately I've been trying to avoid long pieces because most of my current ideas are experimenting with improvised chaos and occasional bouts of wall-of-noise fiascos that the human ear can only take in small doses. The current project I'm working on does have a piece that tops out at about 9 1/2 minutes, but most of them are under 6 minutes long.

^ This.