I’ve noticed that a lot of new GPS devices are “widescreen” (i.e., 16:9 ratio instead of 4:3 ratio). Call me crazy, but… isn’t a GPS interface actually better in the traditional full-screen aspect ratio? I’d rather see more of what’s directly ahead of me on the map than what’s directly to my left and right. For both televisions and computers, the wide aspect ratio makes sense: Movies are filmed that way, and documents can be viewed side-by-side. But I think they need to draw the line somewhere—based on the actual use of a screen—and that line should have been drawn before GPS devices.
I like the way BMW has done it: The map portion is a standard aspect ratio, with information on the right-hand side, in the "extended" area of the widescreen.
So, it sounds like you want a portrait-oriented widescreen GPS device, like the standard orientation of an iPhone.