Q1:How big of a music fan are you? Q2: How much time do you want to spend fiddling around? Q3: Do you want to use your iPod at other times besides your route?
A: 80gig classic is probubly all you need even if you are a big music person, and is the best choice for the money. If you don't want to spend a ton-o-cash then go for the shuffle, but be prepared to spend sometime moving playlists around. The great thing about the shuffle is that it clips onto your clothing, its its own case.
If I was buying an iPod and I had no budget, 160 classic all the way. But for a budget and for portability without a case shuffle. Be aware though that shuffle don't have a screen so that is the biggest difference. But if you don't mind making playlists, and don't want movies or seeing your music, go for it!