Jon:
Any particular aspect with the installation that you had problems with?
Gee -- I wish I did know how to make A'9 install cleanly. If I did, I'd offer that knowledge as a consulting service.
That is to say that recently all four writers who tried to install it at one customer location had problems getting the A'9 to work properly after installation -- and each person's problems were all slightly different.
And, alas, so too were the responses to those problems offered by Adobe support. In one case A'Support recommended running a cleanup tool, in one case it insisted that the program should install with the same serial number as the Tech Comm Suite that putatively includes A'9 (it never did), and in another case it "punted" and gave the I.T. folks a new, separate serial number to circumvent the otherwise unresolvable installation problems.
In my admittedly subjective opinion, the central problem since Acrobat 7 or so is that the Acrobat installation programs have been so overloaded with processes intended to prevent copied or pirated installation that they've instead become impenetrable barriers to legitimate installation...
Cheers & hope this helps,
Riley