The first is a fully connected setting: the ability to first roll around the house, then out into the street and around town, and then out into the world. Given how much scale-changing the game does already, having house/town/world so sharply divided seems strange. It wouldn't even be hard to do, since it's just an extension of how the game already handles areas, and I think it would add more fun to the game.
The other is a play-control tweak: assign "dash" to one of the unused shoulder buttons instead of the wiggle-back-and-forth thing. While I don't mind having the dash take practice to sustain, what I do mind is that with the current system it's almost impossible to start a dash without the game deciding you're telling the prince to turn before it realizes you're doing a dash command, so you (or I, at least) inevitably end up dashing in almost but not quite the intended direction.. not so bad if the reason I'm dashing is just to cover ground quickly, but some of the bonus presents require fairly precise ramp-dashing to reach.
And, of course, more places and things to roll up. The initial promo shots include one of the katamari being rolled around inside a classroom, so at least that wish is going to be fulfilled.