More ideas:

Acoustically quiet rooms. No concrete pillboxes.
Put insulation between the studs.

Plenty of lighting, but plenty of switch/options too. Natural light too.

Easy to control venting. Invariably rooms get stuffy because another room is controlling the temp, or airflow is poor. And put in Air Conditioning even in cool climates to clean mold and allergens out of the air. The 20% of us with dust or mold allergies will thank you.

Drop ceilings, not acoustic tile against drywall. Why? So you can hang stuff from the ceiling! And easily add/change lights and run wires (like for speakers) over the years.

One of the best things we ever did in a renovation was putting 3 feet of carpeting on the lower part of the wall in the Toddler room. Made it quiet and soft, and saved us from having to repaint where the kids had drawn on the walls and hit it with blocks every year!

A cork wall instead of a cork bulletin board.

W I D E hallways.

A really big storage room with lots of shelves and places to store BIG things too.

A gathering space for kids away from classrooms.
Put a kitchenette in it for popcorn, juice, doughnut holes (and teacher's coffee).

Neil