December Double-Pager #12 - John Byrne's Captain America
During their run on Captain America, Roger Stern and John Byrne created a classic issue that depicted the history of Captain America beautifully within a single issue of the title.
The issue (#329) itself may have been a bit slow (as it essentially was just the Avengers voting on who would be the new team of Avengers), but isn't this a neat two-page spread by Paul Ryan depicting the entire group of Avengers?