I use AlpineQuest for hunting. I haven't really used it heavily, but it does what I need it to do. It can run offline if you cache or download maps in advance. It can also attach pictures to waypoints. I'm not exactly a GPS power user, so there may be more there as well.
The interface isn't the most intuitive to me, but I'm able to trudge through OK for marking sign, trails, stand locations, etc.