I vote Garmin Zumo 660. Specially designed for bikes and use with gloves. Feels more sturdy than the Tom-Tom stuff but it does cost more.

 

RT Zumo 660. Does everything but making coffee. Expensive but well worth it. Get the interfase but, don't let the dealer install.

 

I have a Road Tech 660. Bought it at a dealer open house for 20% off. I have created routes using the Harley Trip Planner, then loaded them into the GPS. Works great.

 

So far I've just used the maps feature on my Android phone (HTC Incredible 2). The downside of this is that it doesn't work properly when you are out of cell phone range because it needs a data connection to load the maps and provide the turn by turn directions.

You can save a route from maps.google.com to your "My Places" and, again while you have coverage, load that route into your maps. You won't get turn by turn directions, but you'll get the blue line on the map.

It's not a really great solution for directions in areas that don't have good coverage, but it's quite nice for the areas that do and, if you're doing the smartphone thing anyway, there's no additional cost.

One other advantage to the Zumo/RoadTech is that, being made for motorcycles, they are operable with gloves on. My phone and most touchscreen units require your bare finger to operate.

 

I use a Garmin 2460, it goes for around $175 and I picked up a RAM handlebar mount for $32 from GPS City. It has a nice big screen and you can download routes too. If it rains, I just put it in a Ziploc baggy....