Central Islip is the best from Hauppauge. More frequent trains than from Smithtown + don't have to transfer at Huntington. The only advantage of Smithtown LIRR is the parking which may be an issue at Central Islip depending upon the time of the day.
There is parking on both LIRR branches (Central Islip or Smithtown) Central Islip is on the same branch as Farmindale which is the closest LIRR station to Bethpage park. However they may have shuttle buses from the Other lines.
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