Well, there are many species of milk, and they do vary a bit temperament-wise. I keep honduran and nelson's milks. The hondos are typically nippy and psycho as babies, but my 6' adult is pretty laid back, though he doesn't like to sit still.
My nelson is a juvie. He's much calmer than the hondos (never bitten) but he is still wiggly.
Pueblan milks are another common species, they're known for being nervous and nippy.. especially babies.
Most colubrids are feisty as babies, and many do calm down as they age. Most species of milk are CBB in large numbers and are easy to find. There are quite a few morphs as well (my nelson's milk is an albino and I've got hypo hondurans too)
Babies do best in a shoebox size enclosure.. depending on the species an adult can live in a 20-30 gallon tank. Any substrate that a BP is comfy on is fine for a milk.
All in all, if your kids don't mind a feisty snake when it's a baby, milks are easy snakes to keep, and very beautiful.
EDIT: forgot to put a word in for kings.. I keep california kings, a greyband king, and a speckled king.
Of the three cali kings one who is an adult occasionally bites (I bought her as an adult) the one I've raised since a baby is very docile, however as a baby he was nippy.
My greyband king is one of the most laid back colubrids I've ever had.. never bitten and he's not even very wiggly.
My speckled king is satan spawn.. though I think she was WC so that's probably why.![]()