Our visit to Mt Vernon was rather costly but ever so pleasant. The docking charge for our stay was $2 a foot added to the $18 entry fee per person. We thought maybe we were back in Florida. The facility and employees sure made us glad we had stopped. Even though literature said this was their busiest time and there were "field trips" happening, we never felt rushed or crowded. Totally a first class place. Our water view on that hazy day was pretty special. In all my trips to DC, that was the one place I'd missed seeing. So it was definitely on the list and got crossed off first.