The lighting is a problem on the NE corridor. In particular, the Acela trains have a wider strip lighting directly over your seat which is on one light setting and is never dimmed. The NE Regionals have a narrower strip lighting above the windows where the sidewall meets the overhead ceiling and has a softer appearance than that on the Acela. The result? On the Acela, the florescent lighting evenly distributed on each car on one light setting gives the car interior a much more sterile feeling than the NE Regional cars even though the lighting on the NE Regionals are also on one light setting.

I also agree with CMK10 that a darkened cabin on LD trains make for a more scenic train ride at night. In contrast, one of the most boring and tedious train trips is being on very slow curves at night on the Acela between Providence and NYP. The lighting drowns out anything that can be seen on this route segment.