I've been non-impressed with Cingular through most of my cell career, but my new phone is quad-band, meaning that it can use at least three domestic types of networks, and this has translated into some pretty darn great coverage. Something to consider, plus their national coverage is pretty good. It's getting harder and harder to be roaming to a different network.
Also, they have a pretty progressive way of handling roaming, you can get a plan that doesn't charge you extra for going to a T-Mobile or whatnot system.
Finally, I would not recommend Verizon to anyone who likes to use technology. They might have great customer service (I've heard this from others) and good coverage, but they explicitly lock out major parts of your phone from you so they can control every aspect of your phone use. You can't transfer ringtones to most of the phones via bluetooth, for instance, because they've disabled that part of the bluetooth stack so you can only get ringtones/logos from them. This extends to other functionality to, like using the phone as a wireless modem for your laptop, so even if you think that the logo/ringtone thing doesn't apply to you, there's a good chance that some aspect of their policies will. Just a heads up, other then that, I hear they're great. A couple of my friends sing their praises, even as they extend their peculiar blind spot to cover some of the 'excesses' of the Verizon marketing department.