I have Topo Maps and the TomTom App on my iPhone 4s (carried over from earlier iPhone versions). If your trip is mostly on back roads/dirt roads that can be found on regular maps, I really like the TomTom app. I haven't used the Topo Maps very much because the TomTom app is pretty amazing and has actually had roads loaded in the map that were really just goat trails in Arizona, Eastern Oregon and Central Idaho. Actually, come to think of it, in three years of riding with it I can't remember getting on a trail/road that wasn't on the map. IMHO the TomTom app is worth the $. It even works flawlessly with my Scala Rider G4 and politely interrupts my music with the turn by turn directions. (The sexy female british accent setting is my favorite!) You can upload routes with the trip planner and there are several good online programs for converting GPX files. Unlike the Topo which requires downloading local maps from a network, the TomTom app is preloaded with maps and also regularly updates for free. This means it works anywhere and you don't need cell coverage.