I'm going to buck the trend and recommend integrated nav. It's expensive, but I'd choose it again. The big screen is great, and little things like muting the radio so you hear directions, voice commands, not having to worry/fuss with chargers, etc., make it worthwhile if you use it more than very occasionally. I'm pretty certain the screen brings other advantages in ipod navigation, car settings, etc. In the end, much less driver distraction than the Garmin in my other car.
I have a touring elite so also have the RES. Great for the very young ones. Agree with those who said control from front seat is the "killer" feature. That said, if kids are 5-6 years or older, you could get a couple of iPads for entertainment for lower cost. My kids are 8, 6, and 3, and the big ones prefer iPads.
Anyway, good luck choosing. On Nav, definitely try one with and one without. Don't just use the nav, but hook up an iPod, use the backup camera, etc.