My DS8, who scored 141 on the NNAT2,99.something percentile has not been challenged in his magnet gifted program and I feel your pain.
The traditional educational system is not designed to, nor can it be expected to, cater to a minority of students. They just don't have the resources. I also do not like conflict and it became clear that I was beating my head against the wall, by trying to get the "gifted-trained" personnel at the school to realize what I was talking about by appropriate challenges.
I have kept homeschooling on the table for both of my kids (I also have a DS6), but they love the social aspect of school, so we just let them go, knowing that they probably won't ever be challenged there.
Outside of school we go to the library weekly, and have a large selection of books at home, too. I buy the Singapore Math Challenging word problems books, also critical thinking workbooks. we watch a lot of NOVA, we play a lot of games...have done chess club...my DS6 was actually giving DS8 some strategy tips as I played Othello against him last night. DS6 seems to be a natural for game theory. We have a membership to the Natural Science museum and go there often, etc. Lately they are having a blast with MadLibs, which will mean that DS6 has the parts of speech down already in Kindergarten, but I have to admit his favorite adjective is "poopy," shouted out with a mischievous cackle.
I don't like to have them do structured enrichment after school, because I feel they've been subjected to sitting still for long enough.
If at some point we notice they are less open to truly challenging ideas or that their self-motivation slows, I'll probably press the homeschool issue with them.
In the meantime, we focus on keeping our out-of-school time interesting, which really isn't a challenge, because the kids are driving it with their incessant and beautiful curiosity.
