The battery life on my iPod Classic blows away the Evo -- I have to keep my Evo plugged into the lighter adapter, and since the charger port is on the bottom and the audio jack is on the top, it's impossible to put the Evo anywhere except the passenger seat. For just driving to the store, I can do without the power adapter, but out of town trips or all day excursions, this comes into play. I considered dumping my Classic once 32GB cards become reasonable, but I've changed my mind on that one.
Not to mention the boombox that I use in the kitchen is made for the iPod, and I love that thing.