"Charlie" fits Clark's personality better than "Chuck" as Chuck has more of a blue-collar, construction worker feel to it (in my opinion, I could be wrong.)
Yes, I remember now. Did you read Alison Lurie's
Foreign Affairs ? It's a very good book. I read it a long time ago, in a French translation, but I'm sure that one very unsophisticated character was called Chuck. For Clark, Charlie is better!
