Hi Mike,
Yes, I think the "Aviation Elite" units classification is a pretty loose one, if you look at their WWII titles and others in the same series. To complement their "Men-At-Arms" series they first came up with an "Elite" military unit series, which were bigger books with more information and more info than the regulation "Men-At-Arms" series, for subjects that required more coverage than the usual MAA version. I think the Aviation Elite Series works on the same theory; the "Aircraft of the Aces" series are 96 pages each, and you can't really cover the history of any particular unit in them, as space and the format of the series doesn't permit it. So the "Elite" series (with 128 pages, and more room for larger photo reproduction and -sometimes-more color pages) was designed to cover Squadron histories, and not all are necessarily "elite" units in the usual sense.
Having said that, I'm sure that the Lafayette Escadrille was chosen for its high name recognition value and ready audience, just as 'Richthofen's Circus' was. And yes, while SPA124 was not very "elite" in terms of the number of victories attained (and Jon G admits this right off the bat) you could say it was elite in other ways. Many of its members came from the wealthiest and most respected families in the states, and some were millionaires' sons. One didn't HAVE to come from "old money" to get in the Lafayette, but it did help. Lufbery, the top scorer by far, was of course one of the exceptions! Troublemakers or ne'er do wells from the wrong side of the tracks, such as Bert Hall and Thomas "Horrible" Hewitt, were persuaded to leave the unit in one way or another if they didn't work out. That, and the fact that this unit was very famous in both France and America almost from its creation (in spite of its modest military accomplishments) adds weight to the 'elite' classification. Its propaganda value was immediately recognized, so it was very well-covered in the pressand efforts were made to keep the standard of conduct high in the unit.
So what other WWI units might actually fit better? Certainly 56 Squadron. The top scoring RFC/RAF unit was No 20 Sqn, right? I seem to recall they also had a VERY high casualty rate - were they 'elite' or not? How about 85 Squadron, or (dare I say it) 60 Squadron?
How about Naval 10? Nah, that's been done.
Jasta Boelcke and Jasta 5 certainly , which have both been subjects of recent books.
Any others?
Greg