A few things... 1 - Good bright colors onscreen - nobody has actually mentioned it, but it helps alot! 2 - Detail levels at different zoom levels - many of the units loose map detail as you zoom out way too fast. The unit/maps that I use allow me to see all the roads 8 miles ahead of me. Probably the best you can do is allow user definable detail level. Garmins are fixed. 3 - Lots of long tracks, turned on by default when you load them, retaining their color when loaded. The idea that Locus has of tuning the color based upon speed/elevation/etc is nice for some users, but they missed it in that when you load tracks Locus sometimes changes the tracks color. Case in point - on some of my bike routes I use dark green to indicate alternate main routes - Locus changes them to blue. Oops. Garmin allows something like 16 track colors, that pretty well enough. 4 - Easy to build and use map overlays... there is a couple of software packages that allow you to do this easily for Garmins, BUT, the one I use only allows the 8 primary track colors, and overlays with waypoints only have the waypoint name and phone number is the information about the waypoint. If you could build an overlay of waypoints that has ALL of the waypoint info - Name, address, city, state, zip, phone - it would be really usefull. 5 - Buttons. Waterproof and enough of them to be really useful. Look at the older Garmins - 60/76, 78, or what I use - 498 (it's an old chartplotter but is intended for dual use - Marine and Automotive. Uses either maps.) 6 - A 5" screen, and maybe a version with a 7" screen. If you make it with different screen sizes, make the software interface the same for all the models. Settable for either portrait or landscape mode.