In the Jeep I have the built-in system that Chrysler calls "uConnect" - which works very well. In the wife's minivan we have a VERY old Jabra that I dug out of a bin somewhere and dusted off. It's crappy but usable with both phones. Might upgrade it if she complains, and would be tempted by the Motorola.
My Garmin Nuvi 370 GPS pairs with the iPhone, and makes a GREAT speaker phone in the car. The caller ID comes up on the screen, and lets you use the GPS to operate the phone. It's actually quite handy.