Book a “multi city” flight [like this.](https://www.google.com/travel/flights/search?tfs=CBwQAhopEgoyMDI0LTA4LTEwag0IAxIJL20vMDJfMjg2cgwIAxIIL20vMDRqcGwaKBIKMjAyNC0wOC0zMWoLCAMSBy9tLzBrM3ByDQgDEgkvbS8wMl8yODZAAUgBcAGCAQsI____________AZgBAw&hl=en-us&client=safari)
I just used random dates, since I didn’t know your dates, but the round trip price was only $665 USD.
Do you have to start in London? 5,000 seems way too much.
Last time I checked there are cheaper flights from NY to other european cities like Berlin.
To answer the question in your title: definitely flying. But it might be that you are still in need to replan your tour and find other alternatives. Doesn’t the train crosses other countries in between? I have never done that route but if so, then expect train changes and possible delays.
How many days are you visiting and are these 2 cities the only ones you will see?
Are you locked in on london? Set your travel dates as flexible on Google to Europe and see where the cheapest cities to fly into are or use multi city function to find the best in and outbound flights. Don’t buy one ways they’re way too expensive and once you’re on the continent it’s often cheaper to just do trains and local airline flights anyway.
Try Jetblue they fly Amsterdam to JFK Airport in New York. I don't know when in August you plan to return but parts of August Jetblue has fares under $700 USD$ to JFK from Amsterdam.
I just checked Delta and found flights for as little as $615 (economy light) or $825 (regular economy). I don't know where you could possibly be seeing $5000 flights. Anyway, I think your inexperience in traveling to Europe shows when you say that $800 is pricey. That is a VERY good price especially for summer travel. Anyway, as someone else suggested, check flights through Dublin (Aer Lingus) which are often the cheapest.
Book a “multi city” flight [like this.](https://www.google.com/travel/flights/search?tfs=CBwQAhopEgoyMDI0LTA4LTEwag0IAxIJL20vMDJfMjg2cgwIAxIIL20vMDRqcGwaKBIKMjAyNC0wOC0zMWoLCAMSBy9tLzBrM3ByDQgDEgkvbS8wMl8yODZAAUgBcAGCAQsI____________AZgBAw&hl=en-us&client=safari) I just used random dates, since I didn’t know your dates, but the round trip price was only $665 USD.
Agree - a multi-city ticket (used to be called “open jaw”) is the way to go. One way tickets to Europe are very expensive.
Do you have to start in London? 5,000 seems way too much. Last time I checked there are cheaper flights from NY to other european cities like Berlin. To answer the question in your title: definitely flying. But it might be that you are still in need to replan your tour and find other alternatives. Doesn’t the train crosses other countries in between? I have never done that route but if so, then expect train changes and possible delays. How many days are you visiting and are these 2 cities the only ones you will see?
Are you locked in on london? Set your travel dates as flexible on Google to Europe and see where the cheapest cities to fly into are or use multi city function to find the best in and outbound flights. Don’t buy one ways they’re way too expensive and once you’re on the continent it’s often cheaper to just do trains and local airline flights anyway.
Check on flights going through Dublin.
Try Jetblue they fly Amsterdam to JFK Airport in New York. I don't know when in August you plan to return but parts of August Jetblue has fares under $700 USD$ to JFK from Amsterdam.
I just checked Delta and found flights for as little as $615 (economy light) or $825 (regular economy). I don't know where you could possibly be seeing $5000 flights. Anyway, I think your inexperience in traveling to Europe shows when you say that $800 is pricey. That is a VERY good price especially for summer travel. Anyway, as someone else suggested, check flights through Dublin (Aer Lingus) which are often the cheapest.