No, I've never read any of his stuff, but John says he's read one of de Lint's novels -- *The Harp of the Grey Rose*. John says he found it "so-so".
I was pretty much listing authors of young adult fantasy literature for Selwyn. There are a number of adult fantasy writers I've enjoyed, but the names don't come too quickly to mind this late in the evening when I'm just about to pack in for the day. :) I'll have to look through my bookshelf sometime, and mention what's there.
Still remember your Gore Vidal *Justinian* recommendation. I keep meaning to see if I have it in my public library, but then I get sidetracked.