I just purchased the Rand McNally unit. It is VERY IMPRESSIVE, I must admit. But, you must update the software with an internet connection before use. As I found out, when using out of the box, it has a few bugs: 75 miles from your next turn, it will be telling you that you need to turn in 200 feet...... and again later it will do the same 30 miles from your real turn. Does get you ready, though! These bugs were fixed after downloading 27 updates. After that, I really-really like it!! It has a load and clear voice system, it automatically zooms in on the details of your turn, and even shows and tells you which side of the street your destination is to be found. And yes, it tells you where the nearest Wal-Mart store or SuperCenter is, and gives you unmistakable warnings for the upcoming state line or weight station, which you can control (mine is set for 5 miles). Of course, it lets you input all the parameters for your truck. It has a cute little straight truck to show your location.
The screen is plenty big.
Anyone else have experience with it?