Delorme PN-60

I would recommend the Delorme PN-60, a professional or prosumer grade device. This GPS allows you to upload your own map files, switch between multiple maps for a single area, including raster images (think aerial photos), and interfaces well with a high power mapping program, Delorme XMap 7. Delorme does have a world basemap and if another map is available from another source the PN-60 will probably receive it

The Delorme PN-60w SE comes with SPOT messenger integration which is cool if you need that capability.