All-Star Cast: The whole point of making the band was to get people who were incredibly talented and who'd been 'sidelined' in their previous projects (e.g., being in the backing band of a solo artist). So by the time they began, all four of them were proficient writers, singers and instrumentalists who'd been very much in demand by others.
All of the members who were incorporated later were also stars in their own right: Felder was a very popular guitarist in the LA area and had been hired by Crosby, Stills & Nash for a tour (an offer he eventually declined in order to join the Eagles). Walsh was already a successful solo artist and guitar hero with international popularity, and Schmit had had over a decade of professional experience in Poco and as a guest musician before he joined the band.
Doubling as Crowning Momentof Awesome, when they were inducted in the Rock 'n' Roll Hall of Fame, the SEVEN of them played 'Take It Easy' and 'Hotel California' together. Watching Randy and Tim singing together the famous 'Winslow' bit, and watching Bernie, Joe and Felder on guitar at the same time is just out of this world.
Black Sheep Hit: Not exactly a hit, but "Journey of the Sorcerer" is really different from their usual material (also, count how many times it's mentioned on this page...).
Career Resurrection: One of the catalysts for their nineties comeback was the 1993 album Common Thread: The Songs of the Eagles, which had various Country Music artists covering Eagles songs, particularly Travis Tritt's request to have the original lineup make a cameo in his video for "Take It Easy". They had a second resurgence in 2007 with the double album Long Road Out of Eden, whose lead single "How Long" won them their first Grammy since 1979.