I haven't worked with this company, but I did see on a separate thread that there's supposedly a company in Florida that for a fixed fee of $45, will buy your entire itinerary's worth of European train tickets for up to either 4 or 6 passengers, at European ticket-office prices. They presumably know all the fare rules and discount options, and speak English and can do the whole thing in a single transaction, so if it conforms to what I recall above, it may be a good option for many people.

The company is Euraide. However that link takes you to their home page, from which it may not be immediately obvious that they offer what I describe above. this page takes you more directly to the pertinant information on their site. I'd be interested in hearing about experiences anyone might have with this option.