Tempting as that $50 or even $100 discount might look, always go with a one-year cell phone sign-up with your provider. The landscape changes so quickly and dramatically, any contract more than a year old will be outdated. And you will be charged that severance fee.
Currently, the overall best phone is the Motorola V3i. They're ubiquitous for a reason. (The original V3 was just as good-looking but sketchy in operation.) Yes, the V3i's 1.23-megapixel camera is weak (but better than the V3's VGA) and yes, the sound could be louder. But besides that, it's a sleek, comfortable superb phone. And iTunes' support (with a decent speaker) is a plus.
Along that line, the new Krzr should debut this month. Its camera is upped to 2 megapixels, and it has a luxurious feel and is a bit thicker and longer than the V3i, but it's also narrower.
The most-asked question: which carrier? Answer: there is no universal answer. Your choice should be based on who has the best coverage in the areas you will most use the phone. How do you find out? All carriers give you a period (usually 2 weeks) to test your reception. If it's not perfect, switch to another provider. Outside of the most rural areas, with today's technology, the reception should be close to perfect.
As for design, in my opinion, clamshells are best; sliders are OK but a tad less solid. As for for the candy bar phones, unless you absolutely don't care if anyone hears anything you say at the most inopportune time, avoid them. A button will accidentally be pushed, and you'll be asking for trouble.