Re: Aikido practicality
I think you should visit local dojos and talk to the instructors. There is an enormous range out there. At some dojos, fit 20-somethings pound each other into the mat for hours at a time. At others, people spend hours working on static movement exercises. At some, the instructor yells at you if you don't hit your partner when he leaves an opening. At others, if someone gets hit by mistake you would think someone detonated a stink bomb in the middle of the mat.
You might also want to be aware of the contradictions in your post. Any school that emphasizes "street defense" is necessarily going to be much more aggressive and physical than one that emphasizes spiritual and mental development. Training time focused on "physical development" is time that can't be spent in more contemplative practices. (Well, assuming that yoga, tai chi, and similar practices don't fit your definition of physical development.) It might be worthwhile to consider why you didn't enjoy karate or boxing, and how you expect other arts to be different.