I see what you mean, he's very utilitarian. The whole, needs of the many vs the needs of the few malarky, which can either work out really well or really badly.
Actually, I'd say he was more deontological than utilitarian. I'd say Renly was utilitarian, as he saw the benefit of him being king for the people of Westeros over the normal line of sucession, as he believed he'd do a better job than Joffrey or Stannis (which he most probably would). Stannis however, had deep set duties that he
has to follow (like categorical imperiatives in deontology), regardless of the consequenses to either himself or Westeros. I suppose you could call that honour, but honour is culture dependant. I mean, Victarion believed that his actions are honourable, and they are to the cultural standards of the Ironborn, but we would obviously disagree.
I think Davos Seaworth is a good example as to why Stannis is just rather than honourable. Ned would've probably just pardoned him if he'd been in Stannis' position, but Stannis saw that, as he said (I think in the book as well as the show) that 'the good doesn't wash out the bad, just as the bad doesn't wash out the good'. So to me, that's justice, rather than honour.
EDIT: Sentient Surfer, this can count as a response to your post...