When you have two sofas or any larger seating arrangement a big coffee table might seem like the obvious solution. But also consider a pair of matching coffee tables. They will keep the focus off one large piece of furniture and let your eye move around the room more easily. One classic coffee table size is 48 by 24 inches so you can plan on that when thinking about your furniture arrangement. A large coffee table is often double that: 48 inches square.
If you get a tufted ottoman consider the depth of the tufts — especially if you expect to eat on it. Crumbs will find their way into the tufting and are not always easy to get out. Round coffee tables aid circulation especially where there are many available seats as in this example. If not every seat can reach the table make sure there’s another surface at hand.