I'm not sure I'm doing this correctly, but here goes. I'm starting to research GPS units in preparation for attending MOGA. I don't know where to start. There are lots of units and vendors out there and I don't know what to look for. Currently, my GPS is the Geocaching app on my iPhone 4, which has a lousy battery life. Suggestions on what features I should look for in a unit would be appreciated. Thanks!Spiritwolf922