Don't forget strange beasts like the Jovian Montressor or the Vornian Mole or the Lightning Beasts that gave the Lightning siblings their powers. More than one issue revolved around recruiting drives (and attempted infiltrations by spies and assorted bad guys). The Science Police! Star-crossed Romances! The Espionage Squad! Brainiac 5's inventions getting out of hand! The Legion of Supervillains!
Besides the flight rings, transuits (not part of the ring but an expandable capsule, to reconcile the differing views on transuits) and telepathic earplugs, the Legion occasionally used Distorters to provide them with hologaphic disguises, I think they were belt-worn discs.
Blasts from the past: the Tornado Twins (descendants of Barry Allen), Superboy and Supergirl, and Monel.
Whatever happened to: the Oans and Green Lantern Corps, Thanagar, other alien worlds established in 20th century, descendant of famous heroes and villains, immortals, etc. Legion writers got alot of mileage out of exploring this question.
A very rich mine, here.