Almost all of the various units from every manufacturer has a headphone output jack, usually on the unit itself these days. If a unit is Bluetooth equipped, it usually serves as the client to the phone - only the bike navigators use Bluetooth to connect onward to a headset or other device and those models have headphone jacks on them too.
The 276c/378/478 happen to be my favorite units of all time, and the latest from the series, the GPSMAP 640 is a large screen device that seems especially nice, though I have never actually installed one on a vehicle.
The newer ones (whether they be the non-waterproof Nuvis - Nuvi 500/550 excepted, because those ARE waterproof) or the Zumos, often have MP3 players in addition to the GPS functionality - on my last two road trips I had a set of ear canal studio monitors (Westone UM2) in my ears and aside from hearing protection, had an amazing repertoire of music, with something like 3,000 songs playing away - nothing better than having Hendrix' Purple Haze blasting away in perfect fidelity while carving through Deal's Gap!!!
The more modern navigators can also be loaded with 'custom POIs' - so, for example, I have all of the waypoints for 'Diners Drive-Ins and Dives' loaded and managed to visit of few that were not far from my route - I must say that Guy Fieri and I do not agree on what constitutes great, funky cuisine!!
More important, I have a speedcam and red light camera database loaded and the unit warns me when approaching one of these, additionally with the warning changing to red if I am speeding.
And that's another thing about the newer Nuvis and Zumo units . . . they contain a database of speed limits that's reasonably accurate - no more guessing whether you are speeding.
The 378/478, Zumo 550 and several others can also be plugged into Garmin's XM radio. You can listen to their music and, in the case of the 378/478 can also get weather maps. Speaking of which, the Zumo 660, which still needs a lot of work -
check out my thread (which itself is due for an update) on the unit, or
read my review on epinions) supports MSN-Direct, which can also do weather maps and traffic updates in major metropolitan areas.
Things have been moving right along in the world of navigators. They do a lot more than they did.
If you have an on-board intercom and you've plugged an MP3 player and/or XM radio into it, you can retain the functionality with less hardware - and I've found that my Autocom impacts on the audio quality - so plugging into the navigator that generates my music, gives me alerts and directions and also gets my phone calls provides a nice, 'higher-fi' source of audio with a simpler, integrated interface.
To a very large degree what you choose will be determined by your specific needs. If you were happy with the Quest and want no more functionality, then a 2720, 2730, 2820, GPSMAP 378 or 478 (with emphasis on the last two) are very good bets - however to one degree or another, all of these does support either MP3s or optional XM as well. Note that some of the models I mention have been discontinued, though they can still be found in the distribution channel.
If you want to up the functionality, then there is a LOT more to whose from, including the waterproof Nuvi 500 & 550, Zumo 660 and 550 (in that order, by the way the 550 is the 'higher line' device) and the GPSMAP 640.
One serious shortcoming (among several serious shortcomings) of the latest generations of navigators is that Garmin has gone to raster scanned video - those very thin, ultrasharp, crisp map displays are gone from the Nuvi/Zumo products - and the latest displays seriously limit map detail so that you can no longer zoom out and see where that little twisty road 5 miles ahead goes without resorting to panning. People who RIDE have all be complaining, but Garmin is no longer the responsive company it once was – they are now the big, impersonal high volume manufacturer of navigation appliances and they seem to have forgotten their roots.
Have I managed to clear things up while confusing you even more at the same time?
Yes?
Then I say . . . mission accomplished.
