Trumpet - King 2055 Silver Flare
Horn - Conn 8D or Holton H181 or H179
Bone - Conn 88H
Euph - King 2280 (a few $ more than the 321, but way more sturdy)
Tuba - I commend you for going with pistons rather than rotary. You might also consider the Conn 5JW
Just my opinions, but I wish you and your kids the best!