While I would love to encourage a Thacher track (and still do!), I want to emphasize the cultural advantages your child will gain spending four years on the other coast. This exposure to the different pace, attitude, climate, peers and parents etc is especially positive and has a lasting effect. It made a big and noticeable difference in my son’s life. The negatives are the cost of travel, the time it takes to get from here to there, and missing events that nearby parents easily enjoy. A cross-country decision is highly personal to be sure, but for us, the best school was in California, our son has always been wired for independence, and we were fortunate enough to have long visits 3x per year at Thacher, and then have him home on vacations. Worked great and we still say Thacher was the best education dollars that we ever spent on our kids, including college.
Final note: from your description, you’d be crazy not to look at the amazing St. Andrews. Get @SevenDad to clue you in on the school.