There was a time when the only way to get across from the Americas to Europe was by ship. In fact, Mark Twain wrote about crossing on a side wheeler. Ships have gotten a lot bigger and much more comfortable since then. If you like cruising and don't mind more days at sea, you can find great bargains on transatlantic cruises. Most cruise lines offer them in spring and fall when they are repositioning their ships from their European itineraries to their Caribbean ones.
Prices vary depending upon how many ports the itinerary offers. There are usually two or three with five to seven total says at sea. Because of so many days at sea, the price is lower. If you are not interested in ports of call, you may opt for Cunard's Queen Mary 2 who makes regular crossings several times a year. It takes six days to cross from New York to Southampton but their are lots of ways to entertain yourself on board with the planetarium, shows, movies, art auctions, the casino, and my favorite, excellent lecturers. The only down side to the QM2 are so many formal nights. They adhere to the if it's a sea day it's formal rule although I hear that may be changing.
Other cruise lines that offer transatlantic cruises have much to keep you occupied as well as you enjoy days at sea. Each ship is unique and may have different offerings. For example the Celebrity Solstice Class chips have glass blowing demonstrations. You may
find a putt putt course on some Princess or Royal Caribbean ships. Check out the layout of the ship, the venues, and of course any theme cruises they may have for the crossings. You will find all sorts of choices.
A transatlantic crossing at a lower price is also a great way to try out a more upscale cruise line that you wouldn't normally cruise with. That's how we came to love Crystal Cruises and choose it for our World Cruise. We know we will enjoy the food, the venues, the service, etc. It's a little more expensive than our usual cruise choices but 108 days is a long time. We wanted to be sure we would enjoy every day of it.