You have to remember that when AT&T and Cingular combined their networks, They became the largest network in the US. Cingular was already the class of the field in the Northwest, and just got better. Verizon is commonly known as the worst quality and coverage. Again, as stated already, different areas have different key providers, but with the merger, it'll be hard to beat AT&T anywhere. Their data packages are very competitive as well.
Verizon won't even let my zoom out their coverage map to see the national coverage, and their NW coverage is very sparse in comparison to the competition.
As far as the phone goes, I'm not horribly impressed with the iphone. Other than a cool whizbang display, it doesn't really break any new ground. I'll stick with what I know works, and my Razr treated me well for a long time. I recently upgraded to the V3xx for free. I get a new phone every year under my premier plan with HP, and I get a 25% discount on my rate plan as well.