Featbase has a nice little write up on George’s role in the sessions:

The Grateful Dead chose Lowell George as producer in an attempt to get away from the ‘in charge producer’ role that they had whilst recording Terrapin Station with Keith Olsen. According to Jerry Garcia; “We chose Lowell George because we wanted someone who understood band mechanics.” Bill Kreutzmann commented in an interview: Lowell was really like a member of the band more. If we were working on a song and he didn’t feel it was going right, he’d just grab a guitar and come into the studio and show us how he felt it. That was one of the ways he’d communicate, and it worked great. I had a tremendous amount of respect for him. Do you have any stories about Lowell George producing the Grateful Dead’s 1978 album Shakedown Street? Paul Barrere: At that time, we were doing our thing as Little Feat, and then when we weren’t doing our thing, I was off doing other things by myself. I mean I knew that Lowell was up there producing but I was somewhere between conscious and unconscious at that time in my life. (laughter) So I really didn’t know what was going on but then I remember he came back with this song Six Feet of Snow that he wrote with Keith Godchaux. As a matter of fact, I mentioned that to Phil. I said, ‘Hey did you know that Keith co-wrote a song with Lowell?’ and Phil said, ‘Ummmmm, no.’ So I said, ‘Yeah! Six Feet of Snow.’ So I did manage to get a lot of stories out of Steve Parish, Ramrod and Robbie Taylor about when Lowell was up there working with them that were hilarious. They sounded like they had a real, real good time. Fred Tackett: I remember when Lowell was up there, he said that one of the recreational activities that the Dead had was to try to dose Lowell and Lowell trying to not get dosed with LSD – and it was every day. Paul Barrere: Every day? Fred Tackett: All the time during their sessions they were always trying to figure out a way to get Lowell dosed – he was really on guard – he was like, ‘They’re not going for the Coca-Cola you know, that’s too easy.’ He said that they finally got him with some postage stamps – he needed one and sure enough they got him. (lots of laughter). Paul Barrere: A recording studio is not the place to be in charge and to be on LSD because there’s just too many buttons too many knobs and too many lights. (laughter) You don’t need any kind of added confusion when you’re working in the studio. I mean it might be great while you’re playing and listening, but boy, if you’re trying to work a console (laughter) I think you’d have some problems.

Of course, there is also the legendary story of how the Dead first met Lowell George during these sessions.