It's hard to beat a gas grill when it comes to ease of use, but you do lose the flavor of smoke that comes from grilling over wood or charcoal. Some gas grills come with a built-in smoker box to which you can add wood chips; if your grill doesn't have one, you can improvise.
Get a small, rectangular disposable aluminum pan and cover the bottom of the pan with a layer of wood chips that have been soaked in water for about half an hour. Put the pan under the grill grate, directly on a burner in a corner of the grill. Turn the burner onto the highest setting until the chips start to smoke, and then adjust the burner settings as needed for whatever food you're grilling.
If the chips stop smoking, you can crank the heat back up to get them going again, as long as it won't cause the food on the grill to burn. Never throw wood chips directly on a a burner, as this could clog the gas line.