I occasionally will look at a package in the off chance it will be cheaper, but with one exception it never has been...and can actually be more.
My only exception was actually an airfare + car package. I had a need to fly home for a weekend while working near IAD for two weeks. I happened to check Travelocity and they had an IAD-DAY weekend package airfare and rental car, for around 15% less than purchasing the flight alone.