What was the reasoning for nixing the dome cars?
I wasn't there, but I have talked extensively with a few Amtrak folks about their equipment plans, and from what I understand there will be two or maybe three car shells across the entire system.
The three are:
1) Conventional Bi-level (Based on the Superliner/Surfliner)
2) Conventional Single Level (Based on the Viewliner)
3) High-speed single-level. (It is possible that if they can make the basic Viewliner shell handle high-speed crash specs, it will be the same shell as 2)
They'll be modular, simple to assemble, and as much as possible, mechanically identical. I'd be expecting as many mechanical systems as possible to be shared among the three car types, in fact. This will simplify maintenance and make spare-part sourcing easier.
Under that concept, building a dome into any of those would be insane. It would require, most likely, an entire fourth body shell type. I personally suspect that there will be no replacement for the Sightseer lounge, for the same reason, although I might be wrong. It might be possible to build them into an essentially standard shell.
In addition, as all Amtrak equipment has intentionally been, it will most likely be as space efficient as possible, providing for the amount of desired comfort with minimal fluff.
This is Amtrak. They want to be a real transportation provider, running real trains intended to get people somewhere. They are, despite Boardman's optimism for long-term funding, expecting funding cuts in the future. These cars will be built to operate with the highest possible degree of efficient operations, just as the Superliners, Viewliners, Amfleets, and even the Heritage rebuilds before them.
Via is off in la-la land, and finds themselves running half the system- less than half the system- they inherited. Amtrak runs, more or less, the same system they ran when they started running. And they run a hell of a lot more trains then they did on May 1st, 1971. Because Amtrak has consistently justified its existence with a lot of very realistic operating concepts.
Look at the sleeper cars VIA bought- the Renaissance cars carry 20 people in 10 rooms (Via SS cars cary the same number, by the way). The Viewliners carry a maximum of 33 in 15 rooms, the Superliners 46 people in 21 rooms. Same car length. The Renaissance LD cars carry 49 people, the Amfleet IIs 60, the Superliner Coach cars 75. While a little less blatant, the VIA LRCs carry 68 passengers, verses the Amfleet I's 70 and the Surfliner's 91.
Meanwhile, if you consider the LD trains like the Ocean, well, a typical Ocean consist is baggage, 5 coaches, 8 sleepers, 3 lounges, a diner, a transition car, and a park car. 20 cars, 13 revenue, 6 non-revenue, 1 baggage. 68% revenue to 32% non-revenue, carrying 245 coach passengers and 160 sleeper passengers, 405 passengers total. An average of 20.25 passengers a car. This is the most Amtrak-like LD in VIA's fleet.
Amtrak's most service car intensive trains is the Coast Starlight. The Coast Starlight has 4 coaches, 3 sleepers, 2 lounge cars, a diner, and a baggage car, 11 cars long, 7 to 4, 70% revenue to 30% non revenue, carrying 300 coach passengers and 138 sleeper passengers, 438 passengers total, an average of 39.81 per car (nearly double).
Amtrak would find it an example of total silliness to suggest they attempt to emulate VIA's circus of a business model. I can see why they'd be offended by a suggestion to put a dome on their cars.