I agree that it's a very accessible park, but it's so big and there's so much to see that it can be overwhelming. I know I've mentioned this in other threads too, but we used an app called Gypsy Guides in Yellowstone and it helped a lot. It's a paid app, but we found it useful enough that I would pay it again :-)
For us, it was kind of a happy medium between being on a tour (we like going at our own pace), while still having a little extra information (I really enjoyed not looking through notes or flipping through guidebooks between each stop!)
-Christine
DD, 9/07
DS, 5/09
and a very tolerant pup