It would be interesting to have an option in US2 that would allow the user to set the oblateness (flattening/ellipticity/etc.) of a planet. It would be even better to have a second option like "Link oblateness and rotation rate," so that fast-rotating objects (for example, Saturn) would be flattened according to their angular rotation rate. I know there are some formulas and other math that can accomplish this kind of thing. What I don't know (since I'm not a programmer) is whether it would be too big of a hassle to implement and make compatible with US2's other features. Either way, it's just food for thought.
Stay groovy out there.