Holopad locations, looking at the tgstation map on the wiki:
AI Core, Upload (obvious places, center of the station)
Station core: HoP Office, Teleporter, Captain's office, Bridge, Meeting room? (between HoP and the bridge): Right next to the AI's room and its holopads, making a total of 7 holopads in a small but somewhat important core of the station.
Medbay: Medbay lobby, surgery observation, cloning pod room, Virology, CMO's office, sleeper room next to Cryo: Right across the hall from the captain's office. Plenty covered already, except for Chemistry. (There is both not much use and not much room for one in the morgue) 13 holopads total now.
Research Division: Mech Bay, Robotics, R&D, RD's office, Toxins main room, top part of Xenobiology, and a point in the hallway more or less equally between the toxins door, toxins storage, and xenobiology: Right next to Medbay, well covered. Maybe add one more if the AI wanted to watch slimes in-holoperson for some reason. Now up to 20 holopads.
North of Medbay/R&D: One in the south of the library and in escape wing, but not the chapel in between the two? Also, the main area of the bar has a holopad, kitchen and hydroponics do not. Dorm and the room before the VR room both have a holopad, but putting one in the VR room would probably break the effect in there. In general, this area is also only a hallway or two from the main core of holopads. 25 holopads total.
West of the Bridge: EVA has a holopad. The Gateway, Tool storage, the room across the hall from tool storage, and Arrivals in general have no holopads anywhere.
Supply Sector: Cargo office, QM office have holopads, Mining dock and the disposals/mailing room do not, but usually no one is in the mining dock anyway unless they've returned or its roundstart. Up to 28 holopads.
Engineering: Atmos console room, the room between Atmosia and the engine room, CE's Office have holopads. Engine Room has dual holopads. I would suggest one in Atmos but its confusing to look at for the untrained as it is without one. 33 holopads with only security unaccounted for.
Security: Courtroom has one, the two rooms above it next to the pod both have one, Warden's office has one, the permabrig has one, and theres also one in the hallway leading from the main hallway. A total of 39 holopads throughout the whole station.