Just got back from two weeks in CO. We hit Mesa Verde, Black Canyon, and Rocky Mtn National Parks. RMNP was definitely our favorite. We tried using the REI National Parks App, only problem is most of the places you want to use it there is no cell service. Anyone have any work arounds for using the app? I think I need to submit an enhancement to let us down load info for certain parks as well as complete check ins and photo uploads that the app would store and then once on cell/wifi it would upload.
I don't know about the National Parks App information, like the various pictures and other information that it might provide, but if you are looking for the ability to see trails and your location on them, the REI Hiking Project app should work for that. You can download an entire state's worth of trails when you have Wifi, then the whole state should work offline and you can see various trails, distance, elevation, locations, etc. Then on your hike you can see your progress on those trails and they also have useful tools like an elevation histogram to show you how much distance/elevation you have left. The photos and other items would have to be uploaded with wifi, but for trail information their apps work quite well.
There are also battery free items called topographic maps. Typically USGS or commercial renditions thereof. Nat'l Geo makes a splendid series, focusing on various national parks.