The Zumo 450 and 550 are clearly the best GPS units around for motorcycles.

 

Heres one that calls out the turn and will fit right in the dash. Not only GPS but DVD's on the road..........YEA!!!

 

I had the same needs as you and selected the 450 from Costco about six weeks ago. Keep in mind the 450 also doesn't have XM functionality, but I don't need that either.

The Zumo has a few glitches, which I've largely worked out, solved through Zumoforums.com after finding Garmin support to be strong on patience and willingness to help but weak on knowledge. Here are a few of them:

1. When storing MP3s on the SD card, divide them up into folders. Dumping 500 MP3s into one folder will cause the MP3s and the map drawing to load very slowly. IOW, music won't start and map won't display till it gets past this ritual. At first the delay was about 5 min., but now after dividing them up into 20-30 folders the time is about 20 sec.

2. MP3 volume connected to the AUX connector on the HK head unit produced low volume even with MP3 volume set to 100% (70% is default). It took me almost a month to figure out that it has two volume adjustments, those for MP3 and navigation, plus a master switch (bottom button on left of unit). Setting both to 100% produces volume on the same level as the radio, CD player, etc. and all is well.

3. For some reason the Zumo will not boot when I start the bike immediately after turning on the ignition (my usual procedure). When this happens only a soft reset (power + "+" buttons) will activate it again, but a delay of 1-2 sec. is enough. I originally had it connected to the ACC switch circuit (O/R wire, switched by ignition key only), then relocated it on the HDI connection near the headlight--but the change made no difference. I have now adapted and count to two before cranking the bike after switching on the ignition. No biggie.

4. I had quite a bit of trouble loading Mapsource (CD) and the 2009 upgrade for City Navigator (download from site) onto the computer. I had to use a download of Mapsource from the Garmin site and have tech support help me with the map upgrade.

Go to Zumoforums.com and read up on the following:

MP3Gain (freeware) - Evens volume on a collection of MP3s (no quality loss).
POI loader (Garmin) - Load POI lists onto the Zumo.
PONI killer (freeware) - See sticky thread on using this.

Also, go to POIFactory.com for many good POI lists, icons, etc. I have all HD dealers, highway rest stops, and Walmart stores stored on mine now. For the first two I've marked as "redlight" lists, which will alert you when you approach these POIs (adjustable in feet).