Gamut, the planet of ambulant gametes, training ground for xenologists.
Buckyball, first two surface landings were quickly torn to shreds.
First called Jötunheimr, after orbital views of its biota,
it was renamed for the discovery that the microtubules in that biota's cytoskeleta
are of fullerene: far smaller and stronger than
Single cells can thus lick ten times their weight in Old Earth dinoflagellates. Tissues in multicellular life have tensile strength far beyond even spider silk's.
Composites have corresponding compressive strength, so that plants and animals can support their own weight at sizes that would collapse on Old Earth: small animals move fast.
Fullerene muscles contract with corresponding strength, and thin fullerene nerve fibres carry signals at near lightspeed — two million times faster than humans'.
At least three extinction events appear due to technological civilisations, culminating in global war. It is perhaps fortunate for humanity that the planet currently has no intelligent species.
Okeanos, planet without surface land or shallows. The two intelligent species in the deep trenches have not yet been convinced by Concordat visitors of the existence of sunlight.
Old Earth, origin of humanity, only habitation in Solar System except for Concordat space stations. Quarantined by Concordat (no Da Silva access) against physical and mental disease. Highly-screened, medically adjusted emigration still (in theory) permitted, but nobody on Old Earth builds Colony Ships now: no profit motive, and the racial survival imperative has been satisfied.
Rock Star, planet-free solar system with several Jupiter-masses total of asteroids, in the toroidal Wada Cluster.