I have a Garmin 265w GPS and I use it to get to ground zero. Actually, I have pretty much moved up to my iPad 2. There is an app you can by for $10 written by Groundspeak that is awesome. The software pretty much automates everything. You have everything you need at your fingertips.
It gives you a list of caches in the area, navigate to the cache, choices of map types (street, topo, and sattilite), attributes, hints, notes, past logs. I'll tell you, this setup is the cats meow.
I use a 3G compatible ipad2. But the app will run on the iPhone. You need the Internet for it to be the most help.
The screen actually shows your progress as you go. It also has a distance to GZ numbers that gets you in the zone. Then you have to look around like folks have said.
Try it, you'll like it.