go to google maps...click on the menu button...then 'More'....click on 'Labs' and activate "Pre-cache map area'......put into the address locator the place you will be in without a data connection while you have a connection.....Long press on a spot on the map and then tap on the flag that pops up......you should have a choice to 'Pre-cache map area'....click on that and your phone will pre-load the mapping data for that area.
Based on the types of antennas in the cell phones, Droid Charge for example, they are AGPS chips. That means the phones only look for a certain set of GPS sats in a specific orbit based on laws and regs by the military. You phone uses the signals to get a location approximation. This type of antenna cannot receive data such as internet like it can of the cell towers. Try GPS Status and GPS Test in the market. They will show you the sats you are looking at during a given moment. You can even look up the sat numbers to see the type of sat and orbit.
I run in the mountains all the time. I have almost no cell signal as it is. Google Tracks is what I use most during that time. It follows me and gives a location based on the sats alone. I put the phone into airplane mode and then check to make sure the GPS is still on. Then I launch Google Tracks.