As mentioned, rectangular tables present a certain advantage in terms of capacity that round- and square ones do not. Imagine having to place all the diners to be seated at this elongated table at a round one – you’d have to have a pretty big round table!. For big dinner parties, it’s best to opt for an elongated/rectangular table, as you get more space for chairs and guests.
One of the first things you will have to ask yourself is where you will be placing your dining table. A round table curiously seems to draw all elements that surround it towards it, thereby anchoring itself (and the chairs) visually more than a rectangular table would. It also takes up less space.