Michael Stackpole (I believe it was Stackpole) has a story about the one time he got to "meet" George Lucas. Basically they took him up to the ranch for a lunch meeting and purposefully sat George at a table near him and waited to see how he would react. Ultimately he didn't freak out and the lunch meeting went fine and he would go on to do the X-Wing books and all the Corran Horn/NJO stuff. That seems to be about as much interaction the EU novel people had with Lucas anyway.
But then you had something like this with the recent Maul game:
"The biggest vision shift, however, came from George Lucas himself. According to one source, Lucas took statues of Darth Maul and Darth Talon - a character from the Star Wars comics from Dark Horse - faced them toward one another, and declared, "They're friends!" When it was brought to Lucas' attention that Maul and Talon lived more than a century and a half apart from one another, Lucas reportedly suggested it could be a clone or descendant that players controlled instead of the original Maul."
The Man's involvement was all over the place. Really though, it sounds like with some of this stuff he had a fairly strong sense of dictation. Why that level of involvement doesn't canonize something, I'll never know.