My ties are about 3/4", but I see many tied quilts with much longer ends (not appealing to me, especially if not cut to even lengths). I tie with the poke method, so that there is very little distance for the thread on the back side. There is no way a tooth, toe, or anything else could get caught on either the front or back side. However, I have seen many loosely tied quilts come in for Project Linus, so loose that you could insert a pencil beween the tie and the quilt -- not good. As for embellishments of buttons and such, I leave those for wall quilts. Certainly for children they are a hazard, but even for adults they can be uncomfortable.
Enjoy tying, and be sure to follow batting instructions for distance between ties.
Dayle