Coffee tables should be the same height as the surrounding seating with 18 inches being a good average (although it will depend on your furniture). If you select a coffee table with a lip make sure the lip isn’t higher than the adjacent seating or you’ll end up hitting your drink against the lip when you try to set it down. The idea is to put your drink down not up.
If you get a tufted ottoman consider the depth of the tufts — especially if you expect to eat on it. Crumbs will find their way into the tufting and are not always easy to get out. Round coffee tables aid circulation especially where there are many available seats as in this example. If not every seat can reach the table make sure there’s another surface at hand.