Patina is often considered the best restaraunt in LA.

http://www.patinagroup.com/patina/

Have not been to the new location downtown at the Disney concert Hall(heard great things), but last time I ate at the old location the cast of CSI was at the next table.

Of course it's expensive, but the service and food are some of the best I've ever had (they monitor where you are in your meal by closed circuit camera so they know when to bring out the next course).