This is a pretty vague question - why don't you ask which ships are best for such cruises?
Which ocean are you looking to cross? It isn't like the old liner days when you had regular schedules between major cities. These days you cross oceans whenever ships are repositioning from one seasonal cruising region to another.
For crossing the atlantic I love Queen Mary 2. Does it in 6 days without stopping, Southampton to NYC.
Most ocean crossings involve port stops in Canaries, Madeira, Azores, Bermuda, etc, and may go to Florida or Caribbean before USA.