I test drove the Acura MDX and went with the Lexus, and have been extremely happy. I am getting about 25-27 mpg depending on how aggressively I drive, which is pretty good compared to other SUVs. The ride is extremely smooth and quiet, and the car has an extra kick when you need to pass up a hill, even with a full car. No real gripes at all.
The 2007 LCD screen is a big step up from the 2006 screens. The interface and all the car controls are extremely intuitive. I love watching my real-time gas mileage.
Small things: back seats should fold flat. At times, inputting addresses into the nav system is cumbersome. It needs an MP3 jack. Bluetooth pairing with my Treo was difficult, but I think it's the phone.