All of the spots that you can take a flying taxi to, like Watchtowers and the Paldean Sights. Pokémon Centers can be excluded. I want to make sure I have all in my save file.
Your House Poco Path Lighthouse Naranja Academy (S) / Uva Academy (V) Grasswither Shrine Mesagoza (West Gate) South Province (Area Two) Watchtower Grand Olive Orchards Mesagoza (East Gate) South Province (Area Three) Watchtower South Province (Area Four) Watchtower Secluded Beach South Province (Area Five) Watchtower Leaking Tower of Paldea East Province (Area One) Watchtower East Province (Area Three) Watchtower East Province (Area Three) Rest Stop Million Volt Skyline Levincia Lighthouse Asado Desert Watchtower Zero Gate Icerend Shrine West Province (Area One) Watchtower Colonnade Hollow Glaseado's Grasp Paldea's Highest Peak Glaseado Mountain Watchtower Casseroya Watchtower No. 1 Casseroya Watchtower No. 2 Casseroya Watchtower No. 3 Casseroya Falls Casseroya Lake (Islet) Groundblight Shrine Gracia Stones North Province (Area One) Watchtower Fury Falls Firescourge Shrine North Province (Area Three) Lighthouse
I went through the Bulbapedia link Mr. Fish provided and cleared out all the Pokemon Centers. If you'd like an interactive map with all these locations marked, you may find one here.
