i have used gaia and i found the detail on the topo maps to be disappointing. how is it for you?
--
Stealing! How could you? Haven't you learned anything from that guy who gives those sermons at church? Captain what's-his-name?" ~Homer Simpson
---
Gaia GPS is a pretty good app for what you are talking about. It doesn't give you turn by turn voice directions or anything, but it does give you access to a number of open source maps (including topographical, which is awesome in the mountains). You can use it online, or select an area of the map, and download it to your iPad so that you can access it when you are out of 3G service. (These maps are huge, which is probably why I couldn't find any apps that just downloaded everything onto your iPad.) You can manage the maps you have downloaded - delete ones you don't need anymore, etc.
