I have found that I am one of the lucky ones who can sleep very well in coach. I do have to say that I am disabled so am in the lower level with only 11 other passengers when full, unless I am on the LSL, but I can sleep well on the LSL coach also. I am a rear bird when it comes to sleeping in coach. I put in my ear plugs, bring my own pillow and blanket and as long as the leg rest works, I am fine. As I am disabled, many times I have the back seat on the LSL to myself as that is the designated handicapped seats, but I don't feel I need to spend the extra money or points for the tiny roomette and I can't sleep rocking head to foot like in the sleeper, did that once and will not do that again, got absolutely NO sleep on that trip. I travel end-to-end on 99% of my trips and sleeping in coach is fine for me, but I understand that others cannot sleep in coach.
I have been picked on by some of the AU members here for expressing my opinion of coach, but I am finding that these are usually few and far between. I have to take a cart or chair to the train no matter where I am, so getting to know how and which stations have red cap or golf carts is something I make a point to do.