Family across country road trip

We spent a month on the road making a giant loop of the US. We booked the big sights well in advance, and a few on the longer legs, but others we used GoodSam along the way by calling as we drove and they hooked us up with campgrounds along the way. Don't know how their service is now, but it was pretty effective in '08. Some of the parks along the way are not right along chosen routes, so I like to know whether my journey 10 miles off our path will be fruitful before I make the needless drive, only to return to the highway and look for another. I like to know I have a place when I pull into the park. Not everyone needs to know. Different strokes...