Yes, the Dead were definitely an extension of the On the Road-beat trip. They toured and played more shows than anyone-heck they had a gypsy village following them around (I was one)...it was WILD!!
They are at once similar and very different from Zeppelin; Zep were all virtuosos while the Dead excelled at collectively creating stuff that was more humble yet could blow thousands of minds-you had to be a part of it-they didn't knock you out with it like Zep did-Zep were performers while the Dead was just the part of the crowd that was on stage playing music.....it would probably bore a lot of Zep fans-until you 'GOT IT'......
They both believed in the magic that music could bring to people and the fact that it was much more important than being just a commodity. They both experienced amazing success that the critics could not explain.....they're both my favorite bands.....similar yet so dissimilar.......similar in what counts to me though; MAGIC!