I have a 54" round table in my breakfast room that fits the four of us perfectly! When my sister and my dad come to visit, we like to sit at the table but rectangular placemats won't work when there are six! So I make placemats that fit 6 perfectly at a round table.
Two different fabrics make them reversible - if you get a small spot at lunch, flip them over for dinner! I like to use cotton batting instead of polyester fleece or batting because you can then use them for hot plates (polyester may melt from the heat),