As far as I can tell, there isn;t a single entity within Amtrak that plans and deploys services in the Lounges. Each Lounge is addressed as a self standing entity. This is very different from the airlines which have complete brand books for their lounges, some even two or three, e.g. United's United Club and Polaris Lounge, very different standards targeted for different customer population.
Actually, I would think that the Amtrak lounges each has a slightly different customer profile, which might suggest that the services and offerings be a bit different:
Boston: Is mostly for Acela/Northeast Regional passengers, the only LD passengers are those of the departing 448.
Moynihan: Mostly Acela/Northeast Regional Mostly, It is the terminus for 4 daily LD trains and one 3-day a week LD train. The only LD connection I can think of is the northbound Meteor with the Lake Shore Limited.
Philadelphia: Almost all Acela/Northeast Regional passengers with a few sleeper passengers boarding the Silvers, Crescent, and Cardinal.
Washington: Mostly Acela/Northeast Regional, but also connections between the Silvers and the Capitol Limited. Serves 4 daily LD trains plus the 3-day a week Cardinal.
Chicago: Major connection point for LD trains. Three trains from the east, one to the south (City of New Orleans), one to the Southwest (Texas Eagle) and 3 to the west (Chief, Zephyr, and Empire Builder.) Also serves business class passengers for Midwest corridor services.
New Orleans: Terminal point for 3 LD trains, one of which only runs 3 days a week.) No corridor service and no business class service.
Los Angeles: 3 Long distance trains (one runs 3 days a week). Connecting station between Chief and Coast Starlight. Also serves business class passengers on Pacific Surfliner.
Portland, OR: Two long distance trains. Connecting Station for Empire Builder and Coast Starlight. Also serves business class on Cascades.
All of these lounges also serve Select Plus/Executive coach passengers (and business class passengers in the NEC).
As far as food amenities, the Acela First Class passengers aren't really looking for much., as they are fed and have an open bar on the train. Sleeper passengers, too, are fed on the train. The Moynihan-style light food actually provides a nice lunch for the subset of passengers who might be connecting to the Lakeshore Limited from a Northeast Regional train, like I did last October. That sort of light lunch might be good to initiate at the Chicago lounges, as there are so many passengers waiting there for connections during lunchtime. Of course, as long as there is flex dining, the salads offered at Moynihan might be a nice supplement for those heading out on the Lakeshore, the Cardinal, the Silvers, or the Crescent. It might also be useful to offer such salads to people boarding the Silvers and the Crescent at the lounge in Washington.
Other than that, most of the corridor passengers are traveling for short distances, mostly between mealtimes. While Moynihan style food offerings might be a nice supplement to what's served in the cafe cars, the vast majority of corridor passengers are riding the train to get somewhere, not to eat, so a basic layout of drinks and snacks is all they really need as an amenity.
The main point of the lounge is that it's a quiet and comfortable place to wait for their train, at least compared to the main waiting room. What people really want are trains that are comfortable, in good mechanical conditions that run safely and on schedule.