So, after months & months (and months!) of drooling over GPS devices, I bit the bullet and went with a Magellan RoadMate 300.
I went with this one mainly because I could get one for half price and because -let's be honest- it's probably more powerful than I need, so no point in buying a bigger mamma-jamma. Right? 98% percent of my driving is to work & back. And having seen the same Magellan technology in the Hertz Never Lost systems, I was pretty sure this would work for me.
After a little tooling around with it, I think even Merrin likes it. Of course, she's quite certain that it's going to get me killed ("Don't play with that thing while the car is moving!"), but I explained I'm just as likely to be not paying attention to almost anything else as I was the GPS, so I think that soothed her nerves.
Now if I could just program it to say "Turn here, big boy!"