I'd probs be more interested about the density and composition of the dirt on the planet. Like, if its fine and soft, or course like sand, or dense like hard dirt. I'd be interested in any peaks and valleys (ie. like hills), because maybe that's an indication of any current, or previous, tectonic plate movement. I'd also like to take a sample of the air in it's specific atmosphere, to see if there are any gasses there different to Earth's atmospheric gases, Who knows, maybe a new atom altogether could be discovered, and binding them with other certain atoms may produce a water-like substance, perhaps indicating that water may have been present on that planet previously- if the conditions were just right? Good question Boxhead.
"Interplanetary" references things that affect multiple planets, usually including our own. For instance Interplanetary travel would be travelling from our planet to another. It would be extra-terrestrial geological features.