" ...but it is a $2000 option and for $2k the darn thing ought to work MUCH better than it does."
John, the NAV system is a $1,200 option, not $2,000.
Have you thoroughly read your NAV system owner's manual? I think you will find your answers there. If you haven't read it carefully yet, it seems premature to be so strongly critical. I have found Toyota/Lexus NAV systems, including my brief-so-far experience with the '07 Camry, to be excellent.
The only time my NAV system led me down a wrong street, she (the voice behind the NAV) had been drinking, but has since entered AA and has since not made another mistake). While I was on the wrong street, I found a great Peruvian restaurant, and ordered the best Pescado Sudado that I've ever had.
Good luck!