We're using CTY for high school (9th grade this year). My son is taking a forensics course designed for grades 7-9 and it's SUPERB. Just fantastic. I can't gush enough praise about that course. The instructor writes up a new lesson every week, and stays in very close touch with the students. The stuff she writes is lively and engaging. The exercises are a lot of fun, and he's learning a ton.
He's also taking "From Structure to Style" which is for grades 7-12. Again, superb, and all the comments I wrote about Forensics apply to this course. It's maybe not as much pure fun as investigating a "crime scene" that your mom made (the cat was the perp), but still very engaging. My son's writing style has improved noticeably after only three weeks. It's that good. Both teachers clearly have a gift for what they're doing.
This is our first year homeschooling, and so I can't comment on other CTY online courses that apply to middle schoolers.
We're using a mix-and-match approach. Thus, my son is doing CTY courses, an EPGY course, an AoPS course, and a distance course from France (he went to French school for many years). For PE, there's a free after-school program in the gym at a local middle school (is there anything like this in your area?). I think he runs more now than he ever did in school. The kids who go to this gym basically play very active games for as long as they're there (2 hours a day 3-4 days a week for my son).
So you don't have to be confined to CTY only, though they are the most organized (AoPS is also very organized). The EPGY classes involve a live online classroom, which is nice. That part of EPGY is really great. And the course he's doing there is also wonderful. AoPS is cheap but moves quickly. But they also don't grade unless you ask them too, which removes pressure (the problems are tough). ThinkWell also has online classes, I think.
The best part of all of this is that after ~8 weeks, he's happy, engaged, and learning. There's no pointless homework and virtually no time wasted. All these courses require work, but not to the grindingly misery-inciting levels that happen at some schools.
