A lip edge or tray top on a coffee table is always a smart choice if you have a tendency to spill your coffee or have kids that will be using the coffee table for snacks and drinks. They’re also good if you entertain often and don’t want to worry about red wine getting spilled on your carpet.
For a perfectly square table you may be tempted to use four matching pieces for a perfectly symmetrical look. However you can get a more intriguing look by using two pieces or groups one in each corner. Try a tall vase or lantern in one corner with a stack of two or three books in the other (and an airy sculptural accent on top).