Paula,
I was waiting until someone else posted a suggestion on Chris's school situation.
I'm torn. I don't know what to tell you.
My daughter is very much like yours. Totally dedicated as a student - loves to make all A's and Dean's List. She studies on the weekends. You call her at night and she's studying....
DS, on the otherhand, sounds as though he has many of Chris's tendencies. He hates to study. Never brought home books until last year. He's happy to skate by on As & Bs. Sometimes he gets a C in math. This year, though, he's in AP History, Physics with a Lab, Trig, etc., etc. -- a full course load. He's cracking the books every night!
I totally see where Chris is coming from about hating school - I did, too. But it sounds as though he's a very bright young man. I know that you have had conferences at school, tried grounding, tried sweet talking.
Even if he doesn't want to go to college, he might want to enroll in a trade school. They will probably look at his High School transcripts. Employers may want to know his performance in HS.... I would stress to him that his poor study habits/school performance many come back to bite him in the butt in the future.

I'm sorry. I don't have any advice for you.