Just to clarify - do you mean a Transatlantic crossing, a fabulous way to travel to New York on Cunard’s beautiful QM2 (a liner, not a cruise ship - different ) or a cruise that goes on to, typically, New England and Canada?
You mention the lack of stops so I’m assuming you mean the TA crossing which is available around half a dozen times a year.
It’s not everyone’s cup of tea but I love it - no jet lag, masses to do, great food, unlimited luggage allowed. On a crossing, as there’s not much to see out there, you can obtain a relatively inexpensive stateroom (cabin) known as an ‘interior’ I.e. no portholes or balcony but you’re just using it to sleep in.
If you want a two-week holiday in the US when you arrive, you can pick up the QM 2 to return. The whole thing in that case, takes a month.
Alternatively, Cunard offer a very reasonable flight back after a few days in New York.
The people at Cruise.co.uk are very knowledgeable and helpful.
Go for it!