Quite a lot of species I would like to see again:
Tholians, Gorn, neural parasites, "Schism" aliens, "Silent Enemy" aliens, "Fight or Flight" aliens, Vaadwaur, Voth, Swarm, Suliban, Xindi, Son'a, Remans, Caitians (live action), Iconians (Star Trek Online version), Tzenkethi (Star Trek Online version), Hur'q (Star Trek Online version), Kzinti, Deltans, Efrosians, Rhaandarites, more The Motion Picture aliens, Roylans, Dominion, Hunters, Hirogen, Species 8472
For people:
Catching up with the rest of the TNG cast and also the DS9 & VOY casts, TOS cast, Saavik, Daniels, Braxton, Arex, M'Ress, Xon, characters from ST: Early Voyages comic on Strange New Worlds, an Andorian cast member on Strange New Worlds (Thelin perhaps?), Robert April, Tryla Scott, Shelby, Mackenzie Calhoun & crew canonized in some way.
Starships:
USS Stargazer (some flashback scenes in ST: Picard season 2, with the Stargazer novel characters canonized)
USS Challenger (with Captain Geordi LaForge)
USS Aventine
USS Emmett Till
USS Verity (though I would like them to hold off on making it an Odyssey and more so a forerunner of that class)
Daedalus-class
Luna-class (in live action)
Merian-class
Steamrunner-class
Saber-class
Akira-class
Nova-class
Stations:
Frontier-class station made live-action