I use Backcountry Navigator that a3dhunter mentioned. As he said, you can download the maps for the area you will be in BEFORE you go there so that signal isn't an issue. Also, it does not need your phone to have phone signal as it can "talk" to the GPS satellites directly using your phones GPS receiver. The latest version is also supposed to help with the gray tile issue he mentioned.
As far as being able to see detail on a GPS, I still prefer to have a map with me when I want to look at the surrounding area or look at details like where draws/saddles/springs and so on are. The GPS is nice to show me where I am on the map, but I don't like to depend on it as my whole/sole navigation solution/tool.
And finally, there are some neat stoves out there, like the BioLite, that use thermo-electric generator (TEG) technology to convert the heat energy from your stove into electricity that can be used to charge or power personal electronics. They are a nice alternative to solar panels since they work when it is overcast and you are going to be boiling water anyway. The BioLite is a wood burning stove with the TEG attached to it so you would need wood instead of isobutane cannisters. There are also pots with the TEG built into them that you could use on any stove.