I guess I subscribe to the Keep It Simple Stupid mantra. First I don't like cupholders gps nanos doohickeys etc... mounted on my handlebars. Second is I'm always gonna pull over at some point food, gas check the iPhone for maps/ messages. Third the less distraction the better JMHO.

 

You can get a Garmin 1450 for less than $150.
4.4"W x 2.5"H

nüvi 1450 includes advanced navigation features to take the worry out of traveling. With route planning you can save 10 routes, specify via points and preview simulated turns on the 1450's large screen.

In addition, nüvi 1450 automatically sorts multiple destinations to provide an efficient route for errands, deliveries or sales calls.

A trip log provides an electronic bread crumb trail of up to 10,000 points, so you can see where you've been on the map.

 

If you really like to keep it simple you wouldn't have got a bike with bags, trunk, windshield, radio etc.