I do the same thing, speedracer. I pay attention to what sort of wants a child rolls up and pick their aspiration based on that trend. Of course, that tends to leave romance aspirations out, as a child will never roll kiss/woohoo wants (thank goodness) but since I don't particularly like romance sims, that's fine with me. Then there are the children that have ADD (have best friend, buy a shrub, gain a skill point, play with family member)type of wants and those are harder to pick aspirations for, so I just make their aspiration based on their personality points.