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.
Another consideration is how it will sit on your floor or rug and if it will damage those surfaces. Splintered table legs or rusty metal bases can scratch or stain the flooring. Secondhand stores sometimes leave those areas unrefinished so be sure to check. Sculptural wood coffee tables tell their own story and can add a natural element and warmth to a room with multiple upholstered pieces. Sealers and of course coasters can help protect the surface from water damage.