Speaking of Aluminum Wheels, most dually installations have alum on only the Outers. The Inners stay steel. I think part of it is the OEM lugs aren't long enough to mount two alum wheels since they're thicker than OEM steel wheels.
EDIT: Probably not possible to use dual alum wheels, even by changing the wheel studs to longer ones. Thinking back the way ours (Ford) is, the portion of the hub surface that "pilots" the wheels (supporting the load) probably doesn't extend far enough to support two thicker wheels...
Also, some alum are polished on only one side. In other words, the "dished" side of the rears is polished and the "domed" side of the fronts is polished. Owners of a rig with alum could have three different wheels: Front Alum, Rear Outer Alum, Rear Inner (maybe Spare too) Steel.
We've owned (still have) one vehicle with Aluminum Wheels. They ARE pretty, new. After awhile they get scarred and we had ours professionally refinished. Now that coating is peeling. They're pretty, there's a slight weight advantage (18-wheelers take advantage of that, to stay under max CCWR), and an alum wheel should run a little more true than stamped steel. I'm not sensitive enough to feel any difference.
I'm saying, I'd pass, given the choice again...