I have a Garmin Streetpilot c550 and my wife has a Garmin Nuvi 360...
mine does traffic, mp3's, bluetooth, etc...probably a lot of stuff you don't want...
the one feature I wouldn't do without it TTS, Text-to-Speech, where it says says the actually street names instead of just "turn right in 1/4 mile"...
the Nuvi line is a more compact unit, and you can get the normal or the widescreen versions of most options...
a couple items to look for:
.mp3 (I find this nice when traveling)
traffic (not always useful)
bluetooth (already said you don't care...but it's kinda nice at times)
picture viewer
audio books
headphone jack/audio line-out
I'll tell you what I've found to be the best traveling setup...not as useful around town, though...
make sure yours has an audio line-out...and buy an FM modulator for $20 or so that will plug into the line-out jack...when I'm on a trip, it plays my .mp3's through the truck speakers, then pauses the song and gives me a driving instruction, then the song resumes...then, if I get a phone call, the call can be heard in all the speakers and the mic on the unit picks up my voice pretty good...
maybe too much for you and/or your wife, but I really like it when I'm traveling on business by myself...
the Garmin site has a pretty good "compare" feature...