I would say that any popular night hawker ("mamak") stall/restaurant in the KL area would have good rendang and/or satay. Kajang satay is legendary (much bigger chunks of meat than in KL) but getting to Kajang is a pain especially on a short stay. For the experience, I would probably cab it to Bangsar (very close to Sentral/LeM) and go to either Devi's Corner or Lotus or even the open-air mamak stalls next to Jolly Green Giant. Ask for roti canai with rendang chicken/beef/mutton-lamb, get some satay and you're all set! There are other further out places but the distance makes it less convenient. Plus, after eating in Bangsar you can go bar-hopping or clubbing up the street

I wish I knew some high-end places that serve good rendang/satay but I don't. The Suria KLCC food court seems to be the most civilized place I can think of for those items. They just seem more like street food to me.

As for the Americas, it's easy to get good rendang and roti canai in DC