The RX 350 is a very well thought out car and quality is evident throughout. The interior is sophisticated without "trying too hard".
We got the AWD with navigation, comfort, premium, and tow prep package. The seat ventilation is wonderful in the summer time. I'm also in love with the proximity key and the personalization settings of the vehicle. The navigation takes some getting used to, but the hard drive-based navigation is a lot snappier than portable units and DVD-based Nav I've used on other vehicles.
Passenger and driver comfort are amazing. There's plenty of room for 5 people, though I miss the 3rd row seating of my Honda Pilot.
Key fob/push button start
Lexus service department (hope I'm not there too often, but it's nice)
Scrolling through POIs could be faster in the navigation system. Looking up individual destinations is a snap, but searching for POIs to constantly display requires scrolling through everything in alphabetical order.