Compilations really work if there is more than one artist on the album, but for "the greatest hits" of one particular artist, leave Compilation unchecked.
I'm doing that now. Kind of a pain, but I don't trust an AppleScript to do this for me... too great of a chance for it to mess up. Oh well.
Thanks for that hint. BTW, iTunes support article helps too. I searched for "Album Artist" and I found one that talked about what Compilations were for, etc.