For a short story I plan to write, I was wondering how long it would take individuals to travel from the United Kingdom to America in 1890.
It took between 7 and 10 days, depending on the ship and the weather. The ships sailed out of Liverpool and Queenstown. Here is a notice from "London and Its Environs: Handbook for Travellers" (1889):
It turns out there was an unofficial award for doing this particular trip the quickest in a passenger liner, so we have pretty good records. Of course a typical passage would be a bit slower than one where a captain was pushing to win the record, but the times can be seen as a close lower bound to how long it would take for a typical trip.
In the 1890's the Blue Riband was held by double-screw steamships. A four-time holder was the SS Majestic, which made her maiden voyage in 1890 from Liverpool to New York in a bit less than six and a half days. That wasn't quite good enough for the record. At the time the City of Paris held the record on a run the same direction between those two cities at a bit under 6 days. (The prize was for average speed in knots, so it doesn't translate perfectly to clock time, but there is a relationship).
Now of course if you weren't paying top dollar on a state-of-the-art cruise liner it would probably be considerably slower, but this should give you a ballpark figure and a good idea of the lower bound for a crossing.