Once I get my R, I'll have the TomTom Rider 550 on it. It is much faster than the previous generation thanks to its new quadriprocessor.
It is the same one that I had on my previous bike (Indian Roadmaster). I simply could not live w/o it especially when I organize road trips (as a "captain" of a group of riders).
Here are some photos of how I mounted the Garmin Zumo 595 on my Rocket 3 GT. I used the Brake/Throttle mount that they supplied with it to bolt into the throttle mount. Very clean, brings the unit within decent viewing and it out of the way.
The other thing is a quad lock for my phone which I may or may not keep when riding locally. I mounted the USB that was part of the Garmin cable just behind it so I can power my phone too (instead of using the plug on the yoke). NOTE: The Garmin unit needs to be installed for power to be relayed through the cable (which is a bummer).
2012 rocket3 I moved the ignition barrel to the left side below and behind the gaz tank and put the garmin gps under the sport screen above the instrument cluster far enough in so rain does not interfere with it