I have a garmin 760 and would not leave home without it. I'm more of a regional driver with maybe up to 6 or 8 D/H. Set it on the fastest route, not the shortest, because it will put on a dirt road on the shortest. Always remember to be smarter then the computer. I use the arrival time to calculate when I can make a delivery on time or set it up later. Use the trip mileage to double check what is on the trip sheet.
And if you drive at night the ability to see streets a half a mile before you get there is a life saver and lowers the blood pressure.
I save locations or write down long and lat and put them on a SD card using the Garmin uploader. Wouldn't it be nice if trucking companies or shippers give you the long and lat to enter into your GPS to find customers. This would save miles, fuel and phone calls.
The 760 will allow you to enter different routes and then be able to optimize that route, this would be handy for shopping if you go to several stores or have several deliveries in the same town. If you have 5 routes but run one each day of the week then you could set up 5 routes and just have to click on that route just for that day.
Have a great day.