I'm a big fan of the SS grates. I've done coated cast iron before, and I know Weber's new formulation is a lot tougher than what I've used, but they still eventually fail. No getting around the iron expanding and contracting over and over, eventually cracking the coating and allowing moisture in. With care they can go 5-6 years or maybe more.
SS rods conceivably will last forever with almost no maintenance. I was worried about them not retaining heat, not giving as good a sear mark, food sticking, etc... none of those concerns have come to fruition. I love the SS grates.
SS flavorizer bars are a no-brainer in my opinion. There is no advantage at all to going PCI here, as they will also eventually fail. SS can almost always be scrubbed up to like-new.