Joseph: Since I have never wanted to take a cruise, I never asked any questions about it. I can’t say whether there is more of an issue with a cruise, visiting Miami Beach (or Aruba, Puerto Rico, etc), or walking the streets of Manhattan mid-summer. While a person has the bechira to choose to do an aveira, I cannot state outright that going on a cruise is an outright aveira.
But I do have a question for you: You have to fly somewhere for a business meeting. You board the plane and find yourself sitting next to women who are not dressed appropriately. Are you mechuyev to change your seat? Do you get off the plane?
Many years ago, someone told me that I should not learn or say tehillim while on the subway due to women who are not dressed appropriately. I asked a poseik what I should do and he said: “If the choice is looking into a sefer or looking at the women, choose looking into the sefer.