Global events, there aren't any except maybe TC what is player-driven only and despite the feature not working as intended by what one of the developers said, it was the saving grace for player interaction for a long, long time. I'm talking about global events in a manner that they aren't made by players, but occur on some some fixed/random basis and those events can be about anything crashed vertibirds in random squares of wasteland(of course rare), special supplies for cities witch need to defended, held to obtain.
For example, locals of redding bring news that an enclave armored vertibird has crashed nearby it's city bla bla bla, after 10 minutes a special encounter opens somewhere near redding and players can go scavenge it, might be you find nothing but a crashed vertibird, might be guarded and have to fight with enclave to obtain valuable resource, the encounter of course visible to everyone in the wasteland( or not but easy to find ), or everyone who is in a faction. Don't have to be a vertibird, just some armored veichle. Of course the map spawned with multiple entrance grids, suitable for pvp and what not etc. etc. open for some 20-30 minutes. Taking in consideration the resources possible to gain are very high tech everyone will want to go check out if there's not some gauss pistol, enclave combat armor, 2mm EC, 4.7 caseless(rare, but still possible to find) happens few times in a day = massive player interaction.
Not hard to come up with this shit, hard to implement it.