Fabric is very important when considering a beach robe. One of the biggest differences between a great beach robe and an average beach robe is the fabric used. Good quality beach robes use high quality, 100% towelling at a mid the mid/heavy weight (or thickness). Inside the robe the terry fabric loops should be present as it is these that will draw in the water and dry the wearer. On the outside the fabric should be velour (shaved) so it is soft to the touch. This is also very important to avoid excess sand and dirt capture when worn outside and it will also reduce the chance of the fabric catching and pulling on any sharp objects.
Some beach robes and beach garments are constructed of stretch terry (usually poly cotton). These fabric can feel lovely and soft and are fine as long as you are not looking for water absorption. They are warm and cosy and very soft on the skin. If however you are seeking more utility from your beach robe, especially to dry down and keep warm straight form the pool or beach then I would suggest you avoid stretch terry and look for 100% cotton terry as described above.