Were The Grateful Dead a jazz band?
Phil Lesh (Grateful Dead bass guitarist) talks about the influences of Miles Davis and John Coltrane:
"The basic inspiration for The Grateful Dead was the Miles Davis Quartet with Coltrane or Trane's quartet from the early Sixties. So that was pretty much the inspiration for the way we approach our music."
Miles Davis on Jerry Garcia:
So it was through Bill Graham that I met the Grateful Dead. Jerry Garcia, their guitar player, and I hit it off great, talking about music - what they liked and what I liked - and I think we all learned something, grew some. Jerry Garcia loved jazz, and I found out that he loved my music and had been listening to it for a long time. He loved other jazz musicians, too, like Ornette Coleman and Bill Evans.”
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LuckyCharms: I've always heard The Grateful dead as predominantly a jazz band, with rock, R&B, folk, classical, Motown and bluegrass influences.
Below is some audio I found which displays pretty much all of these styles rolled into one band, and I don't believe there will be another musical collaboration like the Grateful Dead ever again.
This is a compilation of the Grateful Dead playing various iterations of "Feeling Groovy" and "Tighten Up" from the late 60s and early 70s. Some amazing and musically complicated interpretations in here...something nice to put on and give a good listen to as you try to discern each individual instrument. I hear a lot of Miles Davis and John Coltrane influenced themes in here...not directly, but stylistically.
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along with Pink Floyd, Allman Bros, Santana, etc
A friend put it beautifully: 45 seconds of really interesting stuff, followed by 45 minutes of boredom. 
a little bit of country in there too. And although my husband (wrongly 
) called it disco, Shakedown Street was definitely funk.
Grateful Dead music to my ear is music with a heavy influence from Louisiana music genre styles.
This is a note for note recreation of a Grateful Dead jam by Holly Bowling.
This jam was not rehearsed by the Dead...it was played by the Dead only one time, and never again recreated by them. There was no sheet music for this...it was not a composed piece of music. Knowing this...I call this jazz music...unplanned, complex, and completely improvised, and you can really hear it when played by others on an instrument other than guitars.
That the Dead aimlessly noodled is a myth, except during the "space" segment of their shows, where the "noodling" was expected and purposeful. The space segment of their shows were an experiment to see where they could take sound...
That was Phil Lesh who said that quote, not Bob Weir.
Bass guitar player Phil Lesh as an example...
At age four, held his ear to his grandmother's radio and became enthralled with the New York Philharmonic playing Brahms’ First Symphony.
As a young kid, Lesh played the violin in Berkeley’s Young People’s Symphony Orchestra.
At age 14, he traded in his violin for a trumpet. Despite having only a year of trumpet behind him, he soon achieved first-chair position in a semi-pro Berkeley orchestra.
Throughout his teens and early adulthood, Lesh remained fascinated by the world of avant-garde classical and modern jazz, and was particularly intrigued by the sounds of Miles Davis and John Coltrane.
At the College of San Mateo, he became well-known for composing big band music, while continuing his position as first-chair trumpet.
He then took graduate courses in composition under avant-garde Italian composer Luciano Berio.
He lost interest in playing the trumpet and began to focus more on composing music.
He met Jerry Garcia, and Garcia asked Lesh to play bass guitar in his band, despite Lesh never even picking up a bass guitar before.
Lesh learned the bass in 2 weeks, and grew to arguably be the most inventive bass player ever.
Despite appearances, all of the band members, each with different influences, were serious musicians who weren't "playing around".
You be happy too! 
...that were a little overdone. (OK a lot overdone) They played some nice riffs but what they played
were them standing on shoulders of jazz cats that had been played hundreds of times.
I understand I'm being critical...but having the curse of Perfect-Pitch is good and bad at the same time.
The truly hot-licks come from a deep place and make one says "Jesus Christ...Where did THAT come from?
"Never heard that run before" Cheers
You probably know this so excuse my ego.... When someone has Perfect Pitch, they don't need to look at the sheet music.
If you hear a new song..you can write the whole chord structure, all the notes, what key it's in and more...in about 2 minutes.
On the other hand ..When you hear a shitty band, you want to leave NOW!! No..The Dead were no shitty at all.
so I could participate in a deeper discussion with you about this!
I am not a musician. I was a mediocre drummer in a prior life who could barely hold his own. 
I guess I'm talking more about what the Dead's music "sounds like" to me...about the feeling it gives me.
I can recognize good jazz music, and that is what the Dead sound like to me.
It's all very interesting...I was playing the video in the OP on my computer upstairs while my wife was downstairs. My wife yelled up "Is that the Grateful Dead or is that a jazz group"?
That's what prompted my OP, because it got me thinking...
Thanks for the discussion! 