I don't own an iPad yet, but I plan on purchasing one soon. I'm not planning to put my music on it, except maybe a few playlists. I have over 56 gigs of tunes. I had a 64 gig iPod touch, but it met the business end of a parking lot. Right now I'm rocking my old 30 gig iPod (the first video-capable one). Cutting down your portable music by half is an interesting experience.
My eventual plan is to buy a new iPod classic for my entire library. I'm going to hold out until either A) the rumored 220 gig classic launches, or B) the iPod classic gets discontinued and the 160 gig model's price drops. I'll use my iPad for iPad things, and I think I'm going to get an iPhone to do iPhone things.
But I'd buy a 128 gig iPad if it was an option. That was one of my biggest disappointments in the revision.
Oh, and I forgot to address videos: The only videos I have on my iPod at all are lectures from iTunes U. I might put a few movies on my iPad, but I don't think I'll have that many on there.