You've got a lot of options to get between Boston and New York. In addition to driving, flying, and Amtrak, there's the good ol' bus, including Bolt, Megabus, Greyhound, and of course the Chinatown bus service.
But if none of those options appeal to you and my two recent luxury bus trip reports interested you, there is another option. For $69 each way ($5 more than a ticket on Amtrak NE regional), you can stretch out on a comfortable leather seat and enjoy satellite tv, in-seat power, and high-speed internet.
For the last four years, LimoLiner has been offering this "first class" bus service between Boston and New York. The bus is laid out in a 2-1 configuration and feature a 41" seat pitch. The bus is divided into two cabins separated by a bulkhead and lavatory: cell-phone and silent sections. Rather than mingling with the "unwashed masses" at the bus terminal, passengers are picked up and dropped off at Hilton hotels in each city (Hilton Midtown Manhattan on 53rd Street and Hilton Back Bay on Dalton Street in Boston).
Having said all that, I am not going to lie: though this service looks good and the price isn't too bad, I'd stick to Megabus or Bolt. At 1/3 of the price (and even less if you buy in advance), I can't justify the extra legroom and posher seat.
(Tip of the hat to John)