RE: Larger Screen
Let me second the comment on the larger screen.  I had (actually still have)
a smaller unit I used on a couple of trips.  But when I upgraded to the
Garmin 7200 (7" screen) I was really pleased.  Much easier to see and use,
much better data, and the 'Trip Meter' feature or the naviagaion scree both
have a very readable speedometer, really great in a Vanagon where the speedo
is so damn hard to see.  That feature alone is worth it to me.