Yes, I often check the box for avoid highways just to see how a route would go. My Navigon 2100 GPS also allows you to "Avoid" or even "Forbid" highways (meaning interstates). Also you can set it to bicycle or walking speed instead of auto. When driving around in Little Rock back in January, I was trying to find a place I hadn't been before and i set it to avoid highways. It ended up taking me down narrow country roads just about but it did get me there although it's targeting for the address was off by about 3/4 of a mile.
Ah yes, and when I was trying to find a nearby Applebees it had programmed into it already under a POI, it took me to a dead end road with a casket company and nothing else around. I then set it to take me back to a Wal-Mart I had seen and it turns out THAT is where the Applebees was. Gotta love faulty GPS directions.
This past week when I went and bought my 84 Spree, I had the GPS on to help me get to the destination. But I took an exit to a US highway to avoid a bad freeway in Dallas I was told about. The GPS gets mighty bossy when you stay off course too long. It will say, in a somewhat polite voice "Please make a u-turn NOW". At first it says "if possible" but then it just DEMANDS it. After about 10 miles on the other route it finally gave in and told me to continue on the road I was on, lol