I think you're doing it right, Nic H
I do what Gommy does and what you're talking about doing. Having those extra maps can be quite helpful. Often not needed, but nice to have them when you do need them. Since you're visiting so many national parks, I hope you have already visited the National Park Service's website and looked up information about the parks you're visiting. Most of the sections for the parks will have internal maps for the parks themselves. I have found these especially handy. If I were you, I'd find them and print them out. Also any helpful tips on things to visit in the parks, etc.
Navigating vs. finding the small places
Hello Nic-
The text of your original post indicates your primary question relates to basic navigation from point A to point B. If correct, most any sort of highway and/or National Park Service maps will suffice.
I'm a map geek, however, and normally travel with a veritable library of maps. The DeLorme Publishing state-by-state "Atlas and Gazetteer" series had been my favorite prior to October 2007, when the regulars here turned me on to the Benchmark series of state map books when I posted questions here about gearing up for a first-ever trip to California. The Benchmark books offer a rich-textured shaded relief map series in a very detailed scale so that you can identity topographic, and cultural sights quite readily. Whenever my Road Tripping calls for a state which Benchmark publishes, their book will be my first purchase.
Foy