I was a gifted child. Starting from Grade 3, I was in a special program. I went to a middle school that had an entire section for such students, and all my classes were with other gifted children. Then I went to a high school that was exclusively for gifted students, particularly focused on arts and technology. There was pretty much no fault in the system, save for the middle school being horribly overcrowded (which led to discipline problems, and when there's a lot of low-income students mixed with the typically middle-class gifted students, there's some adverse reactions).
It all fell apart in college. I couldn't get any scholarships, because when you're in a program like that, it's HARD. There were very few straight-A students because most of us were learning well above our grade level. I actually ran out of math to take - I did Calculus I (a college-credit class) in my sophomore year, and Statistics (an alternative to Calculus) the next, and that was literally as high as they could teach. Even the "core" classes were advanced - everything except physical education was at least one grade level above normal. Sure, on the state standardized tests we regularly got perfect scores, and my SAT was in the top tenth of a percent, but when a scholarship sees that you were a B-and-C student, they ignore you (it certainly didn't help that I'm middle-class and of no minority group, so I didn't qualify for any of those scholarships, but even the black female students had similar problems). I couldn't afford a good school, and I knew I would be bored out of my mind doing four years at a regular college.
So I did one year at a community college, to knock out the simple stuff cheaply (who CARES where you took Chemistry II when you're a programmer?), and was predictably bored the whole time. I then went to one of those sketchy "get your degree fast!" schools. They taught me absolutely nothing (my high school was several orders of magnitude better), but after testing out of about half the classes needed, I got my B.S. just over two years after I graduated high school, then immediately got a job from one of the internships they'd hooked me up on (I swear those schools have to get kickbacks or something from farming out interns - thankfully I had the foresight to refuse any unpaid internships).
Now, a lot of the stuff that helped me was state-level stuff, and I don't think it's the standard for US education. But if you want to make American education better for gifted children, make that system the standard, then fix the broken college system. Make trade schools for the people who don't need an advanced degree, make it cheaper to get into a college so you don't need a scholarship to qualify, and get some sort of standard in place for comparing grades fairly between unequal schools.