Pompei was SO worth the day trip (from Rome), but save yourself the hassle and rent a car from Rome and make the easy drive to Pompei. The organized tours from Rome make stops at the obligatory tourist stops and the whole ordeal takes much longer than if you simply drove yourself. The cost is about the same. The freedom to do what you want when you want is priceless. Parking at Pompei or Mt. Vesuvius was fine; no need to worry. Driving within Rome was a different story (make sure you have GPS).
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