Re: Is aikido suitable for children.
Totally agree with Jim regarding joint techniques, I don't teach them either. But there are still quite a few that can be taught safely, tenchinage, iriminage, ikkyo, kaiten nage, tai saki, tai no henka etc. Lots of movement and co-ordination to work on.
I also insist that parents of prospective students come and watch a class with their child first, and also watch a class with their child participating, this helps to give the parent confidence in the teacher.