I generally use wide-ish tires for road riding, 32 or 35mm. On rougher surfaces and at slower speeds they are superior to narrow tires IMO.
Above a certain speed (someone above said 15mph) the aerodynamic resistance of the tires outweighs any difference in rolling resistance. When looking at the whole bike+rider+wheels system, at higher speeds, rolling resistance is a very small part of the energy equation.