Hi ZA Cachers - I hope you realise what a fantastic tool Google earth is in helping you plan a caching trip, as you can open .gpx and .loc files directly into Google earth and get an drill down overview on where caches are most dense (less walking) with the option of having a map view (instead of the aerial photo view). This map view is however more for first world places
I am just back from London where I had half a day free for hunting caches. I could plan the whole hunt from home in Cape Town, before I left.
Find the spot you will visit in google earth, get the coordinates from google earth, do a cache search for all caches near that coordinates (at geocaching.com), mass download the .loc files. Go to google earth and do FILE-OPEN and mass select the .loc files for the caches.