I'm definitely down for the 128GB option. The apps, particularly for video-creators are rapidly becoming more demanding, and allowing more ability to craft large-scale projects. If anything, they're the kind of people who may have the highest potential to use up more space for work. Even the music programs are getting to the point they will demand higher space requirements for project data. Of course, its no complaint that we have provisions for uploading and offloading this data to and from the iPad now.
Still, who knows what the future will bring and especially for video creators also using music, a single actual video may be comprised of a number of projects which get edited together. It would be nice to make sure that same machine can do such a thing with the data that is on it without worrying so much about space.
Outside of that, the typical wants as the poster above me said, would be what I would ask for. Apps are pretty much covering the software part of the wish-list. And they continue to move in a direction of power even with what we currently have.
The iPad, right now, is pretty much a Star Trek device. I'm just glad I don't just have to envy those guys on television anymore about their cool inter-connected tablets and such which, in reality, were just mockups.
But as a simple, interest; it would be interesting if they can get to the point where they could have animated backgrounds for the main icon view screen. Of course, people will go crazy with it and create distracting backgrounds, but I wouldn't mind having something akin to a slow moving cool simple gradient plasma effect behind the icons. Considering with the iPad, Apple already long since nailed the idea of how to show video running with extremely low power consumption. They already had 10+ hour straight video-playback per charge with iPad 1, in their video app.