I would consider that room big enough to work with all but the biggest floor standers. I think the more important question is: do you prefer the sound of monitors or the sound of floorstanders. Where do you come in budget wise? That may play a more important role in the situation.
I believe it is smart to question the characteristics of the room like you have, though.
I believe it is smart to question the characteristics of the room like you have, though.