That's kind of what I was thinking, but you see so many booties with really cute buttons. Then the pattern will say, of course, a baby wearing booties w/a button should never be left alone, should be supervised, etc., but in the REAL world (where people accidentally leave kids in hot cars) you never know.
I made one that has little yarn overs along the top and you thread a ribbon through it, doesn't work well for a boy, though.
In the winter here (Lake Tahoe) it doesn't much matter because they have real boots or a car suit on if they go outside, but inside they need little booties because it still can get cold. I just remember Tom had some from the Gap that didn't stay on no matter what, so I think he just wore socks!
I wonder if you sew tiny magnets inside the knitting or sew on velcro. Ribbing in light yarn may have to do though, and forget the cuteness factor.