> absent dismantling the gas giants themselves, you're not going to do anything very interesting do the dynamics of the solar system, regardless of what you take apart, or how you reconstitute it.
I would consider reconfiguring available materials to achieve more usable surface area to be interesting (not to mention potentially useful if we manage to accomplish it someday).
However, what's "interesting" is highly subjective and dependent on context. Perhaps you meant something different by "you're not going to do anything very interesting" than the way some of us are interpreting it?