If you did the first one, you'd just need to glue it in the middle. The triangle ones would need wire strung unless you're very, very precise on hanging it on the triangles. So, yeah, I'd go with the saw tooth one.
If you aren't wanting to attach ribbons or anything else and the sides are painted, just use 3M Picture Hanging Hooks. They work very well, almost everything in DD's room is hung with them. They are basically the 3M version of velcro.