chaplaintzvi,
I said in an earlier post that if the specific situation demanded, it is appropriate to allow an occasional day off. The specific situation here was not presented as that, but rather, that the kids wanted to go to The Great Parade.
One poster responded that there’s no such thing as too much time with kids, to which I demonstrated, in my sarcastic way (good pickup), that it seems to be easier to spend time with the kids (with no specific need) at the expense of learning than at the expense of losing money by taking a day off of work.
I will point out the same thing about your son and the shiva; the one who learns was available, the ones who work or go to school were not. Of course, the fact that only he drives might have been the only deciding factor, in which case it might have been justified.