I got the Expedition on the way there, and Vistadome back (mainly because those timings worked rather than anything else)
Expedition: comfortable, clean, lots of windows (including in the roof). Free soft drink, pretzels, and disgusting chocolate thing.
Vistadome: pretty identical train and comfort to the Expedition, as far as I remember. You gained a slightly bigger snack (little pasta salad and dessert), a one-man 'dancing' show (you can't really dance in the aisle of a train, especially on those tracks), and some weird fashion show which went on far too long, to try and sell you some clothes. Local beer (Cusqueña) available for S/.7
Personally, I much preferred the Expedition - cheaper, just as comfortable, and some peace to enjoy the scenery, rather than music blasting out and a man in a mask attempting to drag people out their seats...
Hiram Bingham is more of a package tour option, including entrance to Machu Picchu itself, and a guide:
* On-board meals with Peruvian wine, Cusqueña Beer, soft drinks and hot drinks (brunch on outward journey, dinner on return)
* On-board entertainment,
* Guides
* Bus transfers
* Entrance to the Machu Picchu Sanctuary
* Afternoon tea at the Machu Picchu Sanctuary Lodge
* Pre-dinner cocktails
Obviously a
lot more expensive than the other two options - not worth it for me, but I can see why people would be attracted by the more luxurious and hassle-free option.
As
JohnnyColombia points out, the trains actually leave from Poroy. We went to Ollantaytambo instead, further down the tracks. It is a lovely place to spend a couple of nights, and there are more trains from there. We got the first train of the day, didn't encounter any queues really, and got to site by 0830 - not as early as staying in Aguas Calientes, but still while it was fairly quiet and cool.