(Been reading this board on and off for a while, but now I actually have something to say that's constructive! Yay!)
We bought a house in Arlington because of the same amenities that the OP wants - proximity to Cambridge's jobs, excellent subway/bus access, vibrant culture, high civic engagement, lots of people in high tech and academia. But that was before we had a child. Turns out that Arlington's school system, while good, is not as good as some of the more expensive Boston suburbs... and it's especially thin for highly gifted children. I know several such kids who are homeschooled, and several others who go to private schools.
But we stayed in Arlington, because we just weren't sure about pulling up stakes and moving to a much more expensive house, just for the option of public schools we may not ever use anyway! We saved our money, swallowed hard, and looked at private schools instead. (DS is in K this year.)
We tried one school, but it wasn't a good fit - they differentiated, but not enough, and he was bored and stressed. In January, we transferred him to The Birches (http://birchesschool.org), a new "one-room schoolhouse" in Lincoln. Much better! It's a multi-age classroom, not exclusively for gifted kids, with a ton of science and nature work. He works at his own level in math, Spanish, writing, etc., but he can still be a kindergartner socially. And the teachers are fantastic. They really "get it" about gifted education.
Stepping back a bit... one of the interesting things about the Boston area is that when parents get frustrated enough to start their own school, they do. :-) Several schools around here are very new: Birches, Tremont, and Acera (formerly Anova), just to name three. Plus homeschooling groups, and math programs, and "maker spaces" like Einstein's Workshop. There's a *lot* of entrepreneurial energy around here. Definitely don't limit yourself to the public schools, with a gifted kid! Such kids, especially those with unusual combinations of abilities and asynchronies, are not served well in Massachusetts schools. GT education is severely underfunded here (though MA schools are good overall, compared to national averages), and MCAS/NCLB plus budget cuts assure that gifted kids won't be prioritized anytime soon in most towns. Other entities pick up the slack, but at a cost. Be prepared for that.
(BTW, Aimee Yermish rocks. You should absolutely contact her if you haven't already.)
