I think that some limited entertainment (and by that, I'm thinking in the vein of the Empire Builder/Coast Starlight things...or even something as basic as Le Pub on the Montrealer for that matter) wouldn't hurt in the least...particularly for First Class on a long haul. Honestly, even a Redbox wouldn't be the worst thing in the world to add in the cafe cars: Enough people bring their laptops on trips now that you could probably sell a decent number of DVD rentals from one of those machines on one of the CHI-West Coast runs. I've thought about suggesting this to Amtrak, actually, since I think it's something they could hope to break even on, if not make some net revenue off of rentals.
But other than something you could easily integrate to existing services (the Redbox idea), or marginal improvements such as a first class lounge car a la the PPC (particularly if they ever get around to adding cars to trains, since the sightseer lounge will get very crowded with another coach or two added), I don't think there's a good business reason to add gobs of "entertainment" programming.
Edit: The "occasional entertainment" bit reminds me of the old seasonal special trains that would be run. I wouldn't mind if they did an announced "Mardi Gras Special" or a "Spring Break Limited" (not that it would actually meet the definition of a "Limited"...) and added something for a week or two, as it fit the season. Seasonal movies on a wall projection screen in the lounge, again matched to the season, wouldn't be a bad touch, either. I guess the way I see it, something special once in a while wouldn't be bad...so long as they're not breaking the budget for it. Then again...I do wonder if they couldn't find some jazz trios willing to do a show an evening for a week or two in exchange for three hots, a cot, and a bit of money (particularly if Amtrak was willing to let them sell CDs after the show/agreed to carry a CD or two in the cafe on those trains and give them a decent split on the revenue).