I can relate - content for high level readers can be so tricky. Due to my my DD's LD issues we did everything by audiobook and listened in the car. This meant we were able to monitor things pretty closely but it is certainly not easy.
Has your DS done the Percy Jackson or Caine Chronicle series? Based on Greek Mythology and Egyptian Gods they tend to hook high level readers despite being written for kids.
DD really liked Doll Bones and The Graveyard Book. Has read each numerous times. Also Diary of a Mad Brownie. All described as creepy but fun.
I'm a big fan of I am a Genius of Unspeakable Evil and I Want to be Your Class President by Josh Lieb. Hilarious and smart. The Worst Class Trip Ever by Dave Barry is also funny and smart. Both are quick reads but a lot of fun. DD didn't like the sequels to Class Trip due to bullying content.
We rely a lot on classics. The content tends to be a bit more appropriate but it is really shocking how much racist language and content they include. In 1st grade I had to turn off Dr Doolittle because of this. It led to a very frank discussion about right and wrong, societal changes, appropriate and inappropriate language, treating all people with respect, etc at a very young age. I am personally very sensitive to dark characters and themes but DD has always taken them in stride. "If it's part of the storyline I'm fine with it." So I guess it's a question of exactly what language and topics you are uncomfortable with. We try to steer away from frank sexual content but classics do still have some innuendo and reference.
We went through a phase of doing a lot of mysteries - especially Agatha Christie. DD loved them.
We work a lot off those "100 books to read before you die" type lists. Or a local book club member gave me their reading list for the past 5 years.
Another way to go that helped us for couple of years was a kids series called "The Sisters Grimm". It's actually written for kids but can lead you to some very interesting options. The premise is that 2 little girls are the last living descendent of the Brothers Grimm and all the fairytales you've ever heard of were actually true stories. These girls become "fairytale detectives" and have to solve an escalating series of mysteries. Each character they encounter is actually from a fairytale of some sort. One of the girls is all in and playful. The other thinks it's all ridiculous and doesn't buy it at all. So if you have a kid who won't suspend their disbelief it's ok - he can be cynical like that character.
We used these books as jumping off points to read and look at numerous different fairytales. (DD has read Cinderella stories from probably 10 different countries.) We listened to the series on audiobooks numerous times. In fact DD - now 14 and about to start 10th grade - just asked to listen to them in the car again for a long trip.
Don't get me wrong classics have more heft. When DD was 12 some we listened to were A Separate Peace, The Scarlet Letter, Of Mice and Men, To Kill a Mockingbird, Grapes of Wrath, Hitchhikers Guide to the Galaxy and Diary of Anne Frank. He will probably need to read a lot of these for HS English courses so don't know how that may affect your choices.
