(It's in Toronto, actually!)
So my point is that the notion of "subject" is not always applicable. It is probably derived from portraiture: landscape photography often does not have a subject in this sense (although it has one or more points of interest).
Cf. for instance the two photos in the lower left corner of Robert Teague's portfolio:
It would be hard for me to say what is the "subject" of the picture in the lower left corner: the lake? the mountains? or the dark portion of ground? Likewise, in the next picture, which is the main subject: the mountain in light or the mountain in the shadow? On the next photo, it's clearer to me that there is a main subject, the group of round boulders, and the effect is different.
My reading of Robert's photos (and I hope he will not mind my using him as a prop for my argument ) is that they work because of composition, and because all the varied elements hold each other together. I personally really like the light mountain/dark mountain picture, because it's a great example of balance: the salience of each element depends on the salience of the other element. Plus, the third mountain brings just a little bit of asymmetry in order to avoid monotony.
It's like the ukiyo-e of the wave before mount Fuji: negative space is as important as positive space.
So to make a long story short: the composition of your whole picture is important, as an organic whole, and positioning your main subject, when there is one, should be made with respect to the weight of other elements in the picture.