There are multiple trains from Boston to NY every day out of both South Station or Back Bay. There is no need to book a train this far ahead in advance. You can book it on short notice (a couple of days ahead of time) once you get to Boston, when you'll have a better idea of when you can head down to NY. Worse comes to worse and you can't get onto a train for some reason, take one of the many cheap buses that go down to NYC multiple times on a daily basis (Lucky Star, Fung Wah, etc). Travel between Boston and NY is very easy and does not require advance planning.

I always get my tix at the kiosk. The ticket is purchased and confirmed. You just take the printout to the station, stick it under the scanner and it prints out your ticket. Never a problem!

You can book it on short notice too, although the acela is usually full, I don't think the regional sells out often.

I'm reasonably sure you can change your ticket with no penalty, but do check with the website to confirm that.

Once you are in the US and know which train you want to ride, you can call 1 800 USA RAIL and speak to an agent. You will get a reservation number (6 letters & numbers). You can have them emailed to you if you have access to a printer.
Otherwise, you can go to the ticket window in Boston South station and give the reservation number and they will print out your ticket up until about 15 minutes before your train leaves.
An "open" ticket that can be used anytime within a year costs much more than a ticket for a specific train. The Acella is a nice fast train that makes fewer stops but it costs much more to arrive 40 minutes faster to New York. The Northeast Regional will have more people but should not be totally packed unless it is a holiday weekend.

OP is going from NY TO Boston. So they would go to Penn Station to pick up tickets. As long as you will be in NY several days before departure you can go online and order your ticket, then take the email and get the ticket at the kiosk. Do be aware that Acela does sell out at times, but the regular train isn;t much slower. And the prices are often less if you buy several days in advance. If you want to switch trains at the last moment you may have to pay a higher price.

Also, be aware you can be asked to show official picture ID to get your tickets so be sure you have your passport handy.

I do the same as china_cat. You bring your printout to the station and scan the bar code, and you get your ticket.

There is a price advantage to purchasing your ticket in advance, especially if you're traveling at a popular time. Ticket prices are different depending on the time of day you travel, as well.

I wouldn't take the Chinatown buses--they have a sketchy maintenance history. But there are two bus companies, Megabus and Bolt, that have inexpensive fares as well. They are well-reviewed, but check on how much luggage you can take with them.

In Boston, you can get off the train at Back Bay Station or South Station, so check to see which is closer to your accommodations, or which has the better subway connection. You can use the route planner at www.mbta.com for figuring out your Boston transportation options.

We have just got back to the UK after a trip to the US (and still buzzing from how brilliant holiday was). I had initially intended to go by train between Philadelphia, Washington DC and then back to New York. There were some reasonable rates on the 'regional' Amtrak service when booking more than two weeks in advance. However we decided to wait until in US due to being under impression that we would not be able to change times of any booking without a penalty. However by this time prices had shot up and most popular trains were very expensive and twice or more higher than what we could have paid in advance. We ended up using 'Mega Bus' which was efficient, relatively comfortable and very good value and easy to book on line the day before travel (albeit in March).
So unless money is of no consideration, then I would try and book the train more than two weeks in advance.

There is definitely a price advantage to booking Amtrak as early as possible so you should look into that, although this is very early to book an August train. When you're ready, book online and pick up your ticket either at the ticket window, or from one of the machines at Penn Station.

I don't think the cost of the Acela, relative to its travel time, is worth it.

I agree with cw that the Chinatown buses should be avoided. They have a terrible safety record. OTOH, I recently took the Bolt Bus RT from NY to Washington, DC, and it was great -- comfortable, reliable, on time, and 1/4 of the cost of Amtrak.

You can book online, however, the fares are nonrefundable. If you want to make a change you must do that by phone, and there is a $4 fee for each change you make. You can put one bag in the compartment under the bus, and take a carry on and a handbag with you on the bus. There's room for overhead storage.

Boltbus is a branch of Greyhound, and the online Greyhound fares are just as cheap as the Bolt bus fares, so you might check the Greyhound website as well.

The buses (bolt and mega) are generally very good, unless it's during rush hour. In the off hours (weekends, early morning, etc), the bus doesn't take much more time than the regular Amtrak. From my experience, I've had my fair share of delays on Amtrak (not Acela) doing this route, so the train isn't necessarily faster.

Both mega and bolt bus have free wifi and outlets. My daughter has also used the Luck Star chinatown bus several times and never had a problem. I believe they also have the wifi.

The disadvantage of the bus is that it is subject to traffic, accident and bad wether. The train runs on time (within 15 minutes) almost all of the time. the buses are late almost all the time - and in bad conditions a 4 hour trip can take 6. Also train is more comfortable. Depends on how you value $ versus time and comfort.

Do NOT take Chinatown buses - they have unqualified drivers, poor maintenance, break all sorts of rules and there have been accidents involving multiple deaths. Bolt and Megabus are still, I believe, picking up and dropping off on street corners versus the major bus stations.

I take the Bolt buses a couple of times a month, and the last time one was over an hour late was during pouring rain shortly after Labor Day (for the Aussies: That's in September!). Tickets run about $10-$20, cheapest far in advance. I'd have to have a really good reason to invest in an Amtrak ticket instead of the bus. Also, they run every hour or so and you can usually get an earlier one as a standby passenger if you're there early.

I take this route frequently. The fare has been $49 each way up to 2 weeks in advance ( except around the holidays); after that the fares can easily double. I always pick up at the kiosk. Not sure what the refund policy is on this fare.

This is also a good option if you want some more luxury with service included.

http://limoliner.com/

Most regular Amtrak tickets (even regular discounted fares) are fully refundable and exchangeable if you cancel them before the time of travel. But some discounted fares (called "smart fares") are not. If you think you might need to cancel or change your tickets, then you need to buy the more expensive ones. If you have some flexibility, trains at off-peak hours can be a lot cheaper than others, and then you wouldn't have to worry about the highly-discounted tickets.

There's no problem with buying tickets in advance and picking them up at a kiosk, but the crucial thing to know about Amtrak is that when you buy a ticket and have a "reservation", it just gets you on the train, it does not get you a specific seat or perhaps any seat at all if the train is oversold. The only way to get a seat assignment is on an Acela train, and those are (as many people point out) quite a bit more expensive. But a lot of people get those tickets so they know they'll have a specific seat. It's really a mad scramble at Penn Station when a train is called, and since a lot of people travel individually on Amtrak, seats are snapped up very quickly. I've wandered for quite a while to find two seats together.

Thanks everyone for your good advice. Think I'll wait till a bit closer to my travel time and book then. I do want the comfort of knowing I have an assigned seat as I will be travelling alone so might just pay the extra for Acela train. I assume I could collect my ticket from a kiosk in LA or Vegas? That's where I'll be first before I head to New York and at least then I will know I definitely have my ticket.

Sorry - there are no assigned seats. The reservation means that you will have A seat - not any particular seat. And when the train comes in many seats will already be taken. You need to find a seat that is not already taken.

In NY you can use a Red Cap to handle your luggage (for a tip). They will take you and your luggage down to the platform before it is announced to the general public - so you can board as soon as those getting off in NY exit - giving you the best choice of seats that are left. Otherwise everyone is rushing to the stairs and running down at once and whoever gets there first has the best choice of seats.

Don't know where the info on Acela and reserved seats came from. I have taken it to Bostonnumerous times and there are no seat reservations - at least in coach. There may be reservations in the Business Class - but god only knows what that costs.

The conductors/ ticket takers tent to use their authority to insist that single travelers sit together so that pairs and groups of 4 can sit together.
Don't try to claim an empty seat beside you with a personal item.
I haven't been to NYP since October 2001 and have never been to BOS but If I were to make the trip I would take the Northeast Regional. The NE Regional takes 40-45 minutes longer for the route than the Acella. If it were an hour or more and I had a critical time to be in either city I would consider spending more for the Acella.

Amtrak uses the term "Reserved" to mean that they don't oversell the train, i.e., you are guaranteed A seat. Many of us have memories of college days standing in the aisle (or sitting on our luggage) all the way from Boston to NYC or at least to New Haven. Last time I upgraded to Business Class, it cost $40 extra between NYC and Boston, but still didn't guarantee a specific seat. But it has been many years since I took Amtrak; I favor the buses.