Another vote for Joe Cocker’s "Mad Dogs and Englishmen", same as for Miles Davis’ " Live at the Blackhawks" sets. The first "Live Dead" double album with ’Turn on Your Love Light’ and ’Dark Star’, The Who’s "Tommy", Stevie Wonder’s "Songs in the Key of Life", "The Name of This Band Is the Talking Heads", The Clashes’ "London Calling" Derek and the Dominos "Layla and other Assorted Love Songs", Muddy Waters’ "Fathers and Sons" with Mike Bloomfield, Paul Butterfield, Donald "Duck" Dunn, and others, Fleetwood Mac in Chicago (with Peter Green at his best, an outstanding blues double album), Aretha did a nice gospel double album at her Dad’s church if I remember correctly too, to name a few. Almost forgot Cream’s "Wheels of Fire", first album I ever purchased with my own money.
Miles Davis "Bitches Brew" and the Beatles double "White " albums get honorable mentions, although not my favorite albums by either of these artists..