stePH, you have recommended books in the past, which Cherryh book should I start with?
Hard to say. My personal favorite,
Cyteen, is one of CJC's densest and most complex works, and lots of people say they had a hard time getting through the first hundred pages (it's 680pp in trade pb). I think a good intro to her "Alliance/Union" milieu is
Downbelow Station which gives a solid grounding in how the socio-political situation present in the other books came about (it details the end of the war between Earth Company and the colonies of Union) -- but again, others have found it tough to get into. Others in this same universe include
Merchanter's Luck, Tripoint, Rimrunners and
Finity's End. All pretty much stand alone but familiarity with
Downbelow Station helps.
Then there's the "Chanur" series that starts with
The Pride of Chanur, a "first contact" story from the alien POV. Speaking of "first contact" stories, many of my associates at the
Shejidan boards regard
Foreigner and its following series much more highly than I do (I read and liked the first three, but I question the necessity of as many sequels as it's getting particularly when CJC has many other stories worthy of continuation.)
There are other SF series that are also tangential to the A/U milieu ("Chanur" is one such, actually -- "Foreigner" is not), and there are also a handful of fantasy novels -- I read one,
Faery in Shadow, and found it a chore, so be warned.
I don't think I've really answered your question ... years ago I started with
Rimrunners, thought it was "all middle" despite the historical introduction, then went on to
Downbelow Station and found it more satisfying (and
Rimrunners improved on the second reading afterward). I guess I'd say start with
Downbelow Station or
Foreigner (be advised that some find the first sixty or so pages of that one to be hard to get through as well -- detailing the arrival of humans on the alien world and their first encounters with the natives -- but I didn't have that problem.)