My suggestion would be the very nice dark gray "Lionel Classics" 2-400E from about 1990. It also has an uncatalogued diecast air whistle in the tender, with a solid-state relay in place of the old plunger-type.
Currently available (C-10, P-10) from Gryzboski's for $895.
Again, a neutral color that would look good with the state cars.