I need to know what is the best map app to use for the following criterea.

Maps need to be cached locally since when i need them most, i likely wont have internet access.
I have no gps capabilities, and can find my way around without the gps unit telling me where i am.
I'll be in the usa, usually in rural areas when i'm using it for maps.
I can give 1gb of storage to the cache for map data if i need to. Much more and i'll have a good excuse to buy a larger sd card
What map app should i use, and what map source should I use?

Thanks
Keith