Quality multi vitamins include names such as Nutriceutical Sciences, Enzymatic Therapy, GNC Mega Man, Twinlab, etc.
MANY nutritionists have recommended dosages well in excess of 100% of the RDA for some vitamins, especially water soluble vitamins, as you piss a considerable quantity of the vitamin out when you take them all at once in the form of a pill, and your body ends up absorbing far less than the recommended 100%. In addition to this effect, the RDA of some vitamins is simply far understated given contemporary knowledge of metabolism.
Your comment about making up any deficiencies through nutritious eating is very true. Most of us who have wholesome diets each day probably could get by without a vitamin at all. However, I know for a fact that my intake of fruits and vegetables is probably far too low, I try to snack on legumes during the day, but most often don't, and by taking a vitamin I help plug the occasional hole where my diet that day did not pass muster, especially given how much business travel I do. I need to function at my prime, and can't afford to take any days off due to sickness so I need to stay well. I think that my supplements in addition to my exercise have helped keep me pretty much sickness free for years. I've had a mild cold maybe once or twice in the last five years and NO flu, not bad for a guy who spends lots of time in grimy, germ breeding grounds such as airports, airplanes, airplane lavatories, and hotel surfaces.