The scale Berk would be an appropriate choice IMO, likely in the brass-hybrid category. Of specific choice would be a 20th Anniversary Polar Express Berkshire, complete with animated figures, including fireman and engineer Smokey and Steamer struggling to put the cotter pin back in the throttle as the Berk accelerates out of control with advanced VisionLine feature of engine swinging side to side over simulated frozen lake
Seriously, anything Lionel can do to upgrade the U-shaped monolithic boiler casting on the existing scale Berk would be neat and appropriate. Even along the lines of the scale S-3 4-8-4 would be cool