National Parks Visitor's Guide
A handy matrix comparing the facilities and amenities of the US National Parks. This won't replace a travel book or in-depth research on the web, but you can't beat it for providing a quick way to narrow down your options.
And if you've got friends like mine I'm sure you know the value of keeping the number of choices people have to choose from at a minimum!
This download is free, but a share or link would be great!