The main reason to get big floor standing speakers is their bass extension. So honestly, there’s no good reason to get big floor-standing speakers if you have a subwoofer. Consider that it’s more difficult and expensive to design a good floor standing speaker, because their required larger cabinet panel are more prone to resonance than a bookshelf speaker with a small cabinet. Thus the same money you’d spend for floor-standers will get you better-quality bookshelf speakers. Or, the same quality at a lower price.
Regards,
Wayne A. Pflughaupt