I'd almost bet that if these folks really did see something, it will turn out to be a new-generation military blimp... Raytheon (among others) has reportedly been working on one that's close to 250 feet long.
Thanks for the link - mystery solved. I saw it last summer - trying to explain it - I said it was shaped like a blimp, huge, very quiet, slow moving and low to the ground. It was going in the direction of our local airport.