So I'm thinking about one of those mounts on your dash GPS units that gives directions, turn by turn. Any thoughts on which models to look at?

TRO

My company bought me a Garmin C330 to carry on trips. I use it in all the rental cars. It works well, the voice prompts are easy to understand. The POI database is sometimes a little dated. I drove to what was supposed to be a Hampton Inn in Kansas City only to find it was now a LaQuinta. There are POI sites to download specialty POI's though. You can't really go wrong with a Garmin, though I would try to get one of the newer, thinner models.
Good luck,

My Garmin GPS V is really dated with limited memory for maps, but it still gets me there. I just keep it loaded with the area I need. If I was to upgrade I'd get one of the Garmin Street Pilots, c330 or the new c530 -- bigger, color display and lots more memory.

The most important question is: what is your geographical location?

I've looked at some of these, such as the Magellan Crossover, but I see a few problems from a survival and/or field use standpoint:

1 - they typically use rechargable batteries. If you're only using it in a car that is no big deal, but if you want to bring it into the field then that is a problem. I personally like units that allow use of common batteries (same thing for digital cameras by the way).

2 - some of them don't seem to allow entry of waypoints as coordinates. I could be wrong on that though. I'm not sure if they let you save a waypoint for your "current" location.

3 - some of them may not allow selection of different datums to match the paper maps you're using (or that you're getting coordinates from).

4 - so far I haven't seen any that allow use of UTM coordinates, which are VERY handy for field work with USGS Topo maps.

These were the main reasons I went with the Garmin GPSMAP 60CSx rather than an automotive-type unit.

Garmin or TomTom. Both are great. I have the Garmin, we put a Garmin 2627 in one of the fire trucks. We like it.

TomTom is the best, its maps are perfect for Europe.
Though, for USA I'd prefer Garmin maps (much more side roads, especially in rural areas, and updating them more often then TomTom, I believe). So, the choice depends on where you are.

And I agree with NightHiker, Garmin is much more versatile. TomTom has in-car-only solutions (excluding their PDA software product).

The folks here always seem to get it right...

This is something I am pretty up on and Garmin and TomTom really are the hot two brands right now. But as always these things change over time.

TomTom has better, more intuitive software by and large. Not surprising given their beginnings as a software company for other makers.

Garmin's strength is the hardware side of the product and the various cofigurations that go with that (portable, mobile, etc).

Easy answer?
If you want tougher, more flexible hardware options that you can walk around with - go with Garmin.

If you are going to mount it in the car - Go with TomTom.

Good luck, you can't go wrong with either.

My DW has a Nuvi300(?) which works very well. It has voice guidance if you like that. However, it is NOT very useful dismounted from the auto.

I just spent 2 weeks touring the Scottish Highlands with a Garmin 60Cx with optional UK maps loaded. It works well in the car with auto-routing capability (but no voice guidance). It also works very well dismounted while geocaching and hill walking.

Not just any Garmin though. The Streetpilot family would be a bit unwieldy as a handheld. The Garmin 60Cx though looks like it would work great in any capacity.