You have your choice: Air, train or bus. All are straightforward. It's a matter of cost, time and convenience.
4 days total in all three cities or 4 in Boston and then the others? In 4 days I would' t try to do more than 2 of those. There is lots to see in each location and sometimes the most memorable moments are unplanned.
Are you flying into Boston? Amtrak goes to all these cities and it would make the most sense to either start in Boston and take the train down to NYC and then from there further south to Washington, or to do the reverse, if flying into Washington. To start in NYC and go up to Boston and the back track to NYC in order to go to Washington would not be the most efficient way to do it. In Boston, there are two train stations, South Station and Back Bay, so you could use whichever is closer to your hotel. I can't speak to how easy it would be for a non-local to use Amtrak; I either fly or drive everywhere and haven't used it for years. Train travel isn't as common here as it is in other countries, but it does make sense for travel between NYC and Boston without a car.
4 nights is not a lot for all three cities, especially taking into account travel times.
If you fly from Boston to DCA. (not IAD or BWI), that's a time-saver because the Metro is right there and the flight is a little over an hour. Commuter flights leave every hour if not more frequently, starting early and going late.
Flying to NYC makes little sense because the NYC airports are about an hour out of Manhattan and as short as the flight may be, you've got time tied up in security on one end and getting into the City on the other. Taxi fare into the city can be as much as 70- . The subway is cheaper/easier and not subject to NYC traffic. Train/bus to NYC easier as they both drop you centrally.Edited: 10:00 am, February 02, 2014
I'm hoping the OP meant 4 nights in each city. Otherwise, that plan would make for one crazy busy trip.
Thank you to everybody who has replied.
Apologies for not making it clear - I did mean 4 nights in each city, 12 nights in total.
We hope to fly in to Boston (probably Aer Lingus from Shannon) and fly home from Dulles.
I do not really like flying so whereas I would have to use planes to get to and from America I would prefer to avoid internal flights. I also thought travelling by train may be an interesting experience (?)
Is it reasonably comfortable on the trains?
We have driven in America and are happy to do so but felt that as we are only staying in cities a car would be an encumberance.
Thank you again to everybody who has replied- much appreciated.
Yes, the train is great between these cities. Nice scenery. Much more comfortable than the bus.
I agree with Caroline. The trains will be fine for Boston to NYC and NYC to Washington. Although trains are not used as much in the US as in some countries, those routes are heavily traveled by business and leisure travelers alike. I really like train travel and find Amtrak quite comfortable. The train also gives you the advantage of arrival and departure in city centers.
You will have a great trip! I have flown Aer Lingus a number of times from Boston to Europe and have always had a good experience. The one thing I remember about my last Amtrak trip years ago was that the food onboard was not that great, so maybe think about bringing your own and having an onboard picnic.
Thank you. I think we will go ahead with this, it sounds as if it will be great. Arriving directly in the city centres will be a definite bonus.
We will take a picnic and sit back and enjoy the scenery.
Thanks also for the information on Aer Lingus.
Thank you to everybody who has helped.