Senior citizens have a number of important financial decisions to make in their golden years. One of the most important is deciding between original Medicare or an alternative plan known as Medicare Advantage (aka Plan C) once they reach the eligible age of 65. With healthcare costs rising faster than broader inflation, choosing the wrong plan can mean paying far more than you need to for medical care during retirement.

Original Medicare has been around for more than five decades, and about 38 million people are currently enrolled in this tried-and-true government-sponsored program. But original Medicare has its downfalls. "Original Medicare" -- which consists of Part A (hospital insurance) and Part B (outpatient services) -- is a one-size-fits-all package, and it lacks key coverage components that many seniors are looking for.