Always purchase travel insurance. It is not the cost of the trip that will be the financial hardship. The worst part of that is that you can't go on your cruise and won't be able to enjoy what you have already paid for. That leaves a bad feeling but it won't destroy the family fortune.
What will destroy the family fortune is a severe illness or accident outside of the country. A heart attack, stroke, severe accident, etc. can set you back six figures in hospital, doctors, emergency evacuation and repatriation (getting your butt back home). These bills often exceed $100,000. This will change your retirement or the kids college funds.
When buying travel insurance You REALLY NEED TO READ THE TERMS AND CONDITIONS Make sure you are covered for pre-exisiting conditions, the policy limits, where you are covered and where you are not covered. Also make sure you know how to file a claim and the hot line number to call if trouble occurs. Many foreign hospitals require an immediate deposit of cash before you will be treated. Remember, you aren't in America anymore and our rules don't apply.
Also, pay attention to what your existing insurance covers. Most private medical insurance does not cover you overseas. Medicare definitely does not but your medicare supplement, Cost plan or Advantage plan might.
Also read the fine print of credit card insurance. Even American Express Platinum travel insurance is not that great. You are not covered for ANY pre-existing condition. Also their car rental insurance only covers the costs to the rental vehicle. It does not cover liability. A friend found this out the hard way while traveling in Germany. He had to fork over $8,000 for repairs to the vehicle that hit him.
My recommendation is: Figure out what travel insurance you have and if it covers you overseas. If not get a good travel insurance policy and make sure it covers pre-existing conditions (usually do if purchased within 7 - 14 days of initial travel purchase) at least $100,000 medical and, at least, $100,000 emergency evacuation/repatriation.
Take care and buy the insurance.