Seeking tech advice: smartphones for geologists

I currently have what I fondly refer to as a "stupidphone." It makes calls. It receives text messages. It stores phone numbers from some of my contacts. I can set it to "silent" mode during class. And... well, that's about all I do with it.

But that's going to change soon.

I'm thinking hard about getting a smartphone. My current cell carrier is being acquired (locally) by AT&T, which means that iPhones are finally an option in Durango. But Verizon also has good service here, which means that the various Android phones are also possibilities. I'm going to upgrade to one or the other, but I'm not sure which. I've talked to my local salespeople, but I'm not sure they quite understand what I want from a phone. In my ideal world, I would get a phone that would allow me to do the following on the road from Durango to Albuquerque or Denver: find my location from GPS, plot it on a map, look up the geology on a geologic map, figure out the direction to a mountain peak in the distance, take a picture of an interesting outcrop, and show it to the world on Twitter. (In my dream world, I would be able to do this while driving through the Navajo reservation, but I don't think any carrier has decent service through much of it.)

So, Internet: what's your experience with smartphones? I'm interested in hearing what you like and don't like about your current phone (especially the iPhone, Droid X, and Samsung Fascinate, though if you love another Android phone, I'd like to hear about it, too.) I'm also hearing about what apps you like as a geologist (or as a non-geologist who knows the kinds of things that I like).

(I know that Android vs iPhone can be a near-religious preference, so I guess I should also say that I'm agnostic. I like Apple products (I've got a Mac at home and I love the iPod Nano I won from my local NPR station), I like Google (Google Earth, the search engine, gmail, blogger...), and I use a PC at work. I could work with any of the operating systems.)

Edit: Given that the first comment gets into the Apple vs Android preference immediately, here's some more ground rules: I want to know what YOU like about YOUR phone. If you're an Android fan, don't tell me what's wrong with the iPhone; if you like iPhones, don't tell me what's wrong with Android. I've kept one comment, but will not publish any others that bash the other operating system.