I'm leaning towards the 20 gig model. The 15 gig would probably be satisfactory for my purposes, with the occasional album swapping happening here and there, but, once you add in the cost for a dock station (which isn't included with the 15 gig), it makes sense to just go for the 20. Right?
Here is the important question - where did you buy yours? So far, every vendor I have found has the iPod for only $5 cheaper than apple.com. Am I missing something?