Pack your own medications. Medications in resorts and airports are often more expensive than if you bought them at home from Target or Walgreens. Common things to have on hand in adult and children doses: Tylenol, Pepto Bismol, Imodium, Dramamine, Benadryl, etc.
Purchase a travel insurance policy. Many people are surprise to learn that their medical insurance does not offer much coverage outside its network. Travel insurance provides coverage for unexpected medical expenses (trip to ER, ambulance ride, medical evacuation, and more). Travel insurance is a trip expense that is non-negotiable, in my opinion, and should be included in your vacation planning budget.