I've just got back from a 10000 K  trip to Mexico and back (Buses to Zamora)
and used a Garmin 350 and Streets and trips 2008 on the computer. In the USA
and Canada the Garmin is excellent the 350 model has text to voice so it
tells you the name of the street or Highway your  to turn on. I found this
feature to be invaluable  especially  in large  older cities  where the
streets  can be pretty  close together.  In Mexico nothing works 100% I
bought Mexico maps from Bica Maps in California for the garmin but these
maps are based on hiking maps and not really suited for a van. The Garmin
would quit often try and send us up or down a mountain on a hiking trail.
The new Streets and Trips has excellent coverage in some of the larger
cities but only the main highways elsewhere. Even the maps we bought in
Mexico don't agree with each other, the GPS is good to show you how badly
your lost. In two tears of using he Garmin I've inly come across 3-4 roads
that were not in the in its database .

Jerry

--
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