I guess I should have searched "SIG" but being a newbie, I didn't know the abbreviation.

Some great points here. I guess I should check with the school district about CTY credit being accepted.
Also, while I'm at it, I assume the abbreviation "DS" refers to "Dear Son."
Polar Bear, thanks for the insight on not using CTY for computer programming courses. We were actually going to do that, since he loves programming with Scratch and he wants to learn other, more advanced languages. After I posted, I checked out a website, code.org, which was recommended to us. He's already up and running there. And to think we were going to pay for what is out there for free! So thanks for the head's up.
Gabalyn & Cricket, thanks for the head up's on the spotty reviews for SIG. I'm going to look them up. We were actually leaning toward CTY at Lafayette next year, because it is only an hour and a half away, and I have a cousin who lives nearby (in a pinch, nice to have family there if someone needs to get there ASAP). We might do Sweet Briar, though, because the class offerings there appear to be more numerous.
We share your concerns about residential camp at this age, but we think he'll be ready for it next year, after a year of a middle school.
Great feedback. I really appreciate your help.