Re: Mamouth caves
Sorry I'm coming into this thread so late, but I've very familiar with the Mammoth Cave area of Kentucky. By far, the best campground is the Cave Country RV Campground. It's near I-65 and only about 5 miles from the park entrance. There are a few other parks. Jellystone (which I do not recommend as it's very hilly, small sites and old. Lots of kids there and if you have kids it's an alternative. Singing Hills is another but it's very old. You can also stay in the park at the park campground, but it is primitive camping. There are RVs there, but there are restrictions on generators.
Cave Country is here:
http://www.cavecountryrv.com/ I've stayed there several times. It's new, very clean, has cable TV, all sites have sewer hookups. They even have a fenced dog run.
If you're looking to rent a car, you'll probably have to go to Bowling Green which is about 20 miles south of Mammoth Cave. I'm sure there are no rental places in Cave City. There may be one in Glasgow which is about 10 miles east but I doubt it.