Why would you want your coffee table to be upholstered? There are two reasons: it is aesthetically pleasing, and it allows the table to do triple-duty. The ottoman can be used as a coffee and cocktail table, it can be used as a footrest, and it can be used as extra seating when needed. For these reasons, it is ideal for small spaces, or for a minimalist decor, in which you want to have as little furniture as possible.
I like this model because of the tufted top and big square legs:
Round upholstered ottoman coffee table pictured: Coaster Round Upholstered Storage Ottoman with Tufted Top in Black by Coaster Home Furnishings