Thanks so much for your response. Your advice totally jives with others I've spoken to. I was able to find a shop who could get me new Lexus alloy rims (in silver finish) at a great price. I am planning on the Continental tires but probably the newer ones called PureContact instead of DWS. The tire dealer said they are rated for 70,000 miles (vs 50,000) and customers report being happy with them.
I also agree with you that there is no reason to expect more from the Lexus dealer. They did try to get "take offs" but could not locate any.
Thanks again!