E.M.
I have a Petunia Picklebottom boxy packback. It is expensive but I have used it every day since my 2 1/2 yo was born and with the addition of a new baby now stuff it with stuff for two kids daily. You can look at them at www.petuniapicklebottom.com, at Nordstrom, or on eBay. I particularly like the functionality of the boxy backpack.