I would like to know how others maintain the outside of their stainless grills though.

Soap water or Fantastic and the important item... a cover.

This was recommended by a friend, but I haven't used it yet.
http://www.bayescleaners.com/bbq-cleaner.htm

Your supposed to clean them?

5 years with my Weber and I only scrub down the grate when its hot with a wire brush. There is lots of buildup everywhere and it looks pretty used and its finally making some nice flavor.

Heat and more heat. If your grill can't turn the residue on your racks into a fine powder in a half hour or so, you ain't got enough heat. I've actually have a Ducane grill for the past 8 years and they "use" to have a lifetime warranty on all their parts. Even though it was completely stainless, the part still rusted away from the heat. I just called a few months ago and low and behold, the company has been bought out (which would explain it being sold at No Ones Home Depot)and now the don't honor any of their lifetime warranties.