One point to keep in mind when choosing a table is how it will influence the social factor of your dining room. A round table is perfect for when you want to encourage conversation around the dining table. Also, it doesn’t allow anybody to sit at the head of the table, which is perfect for when you want to avoid any type of hierarchy.The same is true for square tables; however, square tables take up more space than round ones. And for the same number of diners, it’s better to opt for a rectangular one, as it offers more seating areas.
If you have one formal and one casual dining space, you can really go to town with different chair designs for both. A casual spot will do best with sociable, comfy seating that naturally leads to conversation, whereas a formal setting is where you can play around with luxury fabrics. If you only have one dining room, you're going to need to combine all of these elements in one set of chairs, if possible!