I was going to write the same thing! dooney, lesportsac or kipling are great ideas!when i was a pre-teen, my first "designer" bag was a dooney. they have some really adorable younger "prints", and their bags are really durable. plus, they have the 12 days of dooney right now, and you can get some fantastic deals!
lesportsac is totally cute too. durable and lightweight. as is kipling.