I think what's most important is that it's a school and a classroom where the teacher is willing and able to notice and adjust for abilities. In the very high-performing district at a very high-performing school (10 on GreatSchools, >90% passing the state test) where DD was from K-2, they were incredibly rigid with curriculum and strongly associated model children with giftedness. It was 3 years of raging disaster for DD.
We moved to a lower performing school--it is rated a 5 on GreatSchools, 65-70% passing on the state test--and DD is having a wonderful year in 3rd grade with teachers who are working hard to meet her needs. (In this distrct, TAG starts in 4th.) In this case, the general level of the curriculum is meaningless because DD isn't doing most of it anyway.
Before we moved here, I called the head of the district gifted program and the school principal, and spoke to them each for about half an hour about my child specifically (with test scores in hand) and what specifically they could do to serve her needs. They were friendly, interested, and totally willing to talk about appropriate accommodations. In our old district, the gifted program head wouldn't have given me the time of day and the principal refused to let teachers do real accommodations. In another high-performing district I was considering, the gifted program head did give me a 10 minutes phone meeting but was not very interested in talking about my kid, only about what tests she'd need to re-take to enter their gifted program.
