I've been travelling through the USA , Mexico and Canada quite a bit in the
last 6 years and I use a combination of maps, dash mounted GPS and mapping
programs on my computer. On my first long trip I was by myself and used my
computer on a swivel table I made using the front table socket. This was
much like Franks setup but didn't sit on the dash. It worked great but took
up a lot of room. Now my wife and I travel with our dog so that set wouldn't
work . We use a dash mounted Garmin GPS and maps. We will use Streets and
Trips  on the computer to plan a route and then enter points in the Garmin.
I hae a older Garmin and can't enter multiple stops at one time so we just
go point to point.
  I really appreciate the GPS when we are going through strange cities with
a lot a traffic, I can concentrate on driving and just listen for the voice
commands on upcoming turns.  This works well for us and makes the travelling
much more enjoyable.
  Mexico is another story, even with the most up to date maps and GPS
softwear  I can guarantee that at some point you will get lost. The road
numbers and names seem to change every-time someone is elected . You can
always find your way it just gets more exciting sometimes then you would
like.

Twenty years from now you will be more disappointed by the things that you
didn't do than by the ones you did do. So throw off the bowlines. Sail away
from the safe harbour. Catch the trade winds in your sails. Explore. Dream.
Discover. ~ Mark Twain