Here I am with my second Steve Englehart book in a month, I must be stuck in a run. Anyway Vol. 6 of the Essential Avengers covers the bulk of his run on the book, and it is one of the odder periods in the history of the comic. The majority of this book is taken up by the Celestial Madonna saga, in which Vietnamese heroine Mantis is told she's the Celestial Madonna and the Avengers spend the next year trying to work out what that means. Highlights from the story include the Avengers being led around by 2 talking sticks for three issues and Mantis eventually marrying a tree.
It's not all that odd however, and quite a lot of truly fun Avengers stories are included here as well. The Vision and the Scarlet Witch marry, the Legion of the Unliving is created in order to live up to its name and the time traveler Kang attacks incessantly in three different incarnations (some of which fight each other). So the book has all the fun of a typical mid-70's Marvel comic, but I really have trouble getting around a year long story that ends with someone marrying a tree.