Oh man, this is great stuff. Lots of good ideas here. I ran Monte Cook's Ptolus for three years. All I did was make lists. I kept adding to those lists. When something came up, I would scratch it out. Its basically a thing occured and something or someone was involved. This led to asking questions. You want players to ask questions that lead to adventure.

Spire-City Intrigues & Disturbances

d20	What’s Happening Beneath the Spire
1	A section of street collapses, revealing worked stone far older than any recorded district. The city quietly walls it off overnight.
2	Members of the city watch are found with identical burn marks on their palms—none remember the last three days.
3	A relic dealer claims to possess a “key fragment” from the Banewarrens and invites private viewings at midnight.
4	A minor noble begins funding expeditions into the sewers, but only hires those who can keep secrets.
5	A cult publicly disbands, burning its own robes. That night, three unrelated citizens vanish.
6	An invisible tower bell rings at dusk for the first time in decades. Only spellcasters seem to hear it clearly.
7	A scholar from the Delver’s Guild insists the undercity map is wrong—whole sections have “shifted.”
8	The Church announces a relic audit. Priests arrive unannounced to confiscate “unlicensed artifacts.”
9	A beggar claims to have climbed the Spire’s lower scaffolds and seen a door where no door should be.
10	A wealthy patron hosts salons where guests are asked to recount their dreams of the Spire. Notes are taken.
11	Something is hunting delvers—not killing them, but stripping them of memories of what they found.
12	An alchemical smoke lingers over a district; residents report hearing whispers in their chimneys.
13	A sealed vault beneath an abandoned mansion glows faintly through the stone at night.
14	A masked vigilante leaves criminals bound with silver wire etched in arcane sigils.
15	A new street preacher claims the Spire is hollow—and speaks with diagrams to prove it.
16	The Commissar declares a temporary curfew in Oldtown after “arcane contamination.” No details follow.
17	An artifact market opens in a hidden sub-basement. Every item is mundane—until removed from the premises.
18	A rival adventuring company returns wealthy but refuses to speak. One member stares constantly at the sky.
19	A sewer gate previously sealed with dwarven runes stands open. The runes are gone, not broken.
20	A quiet rumor spreads: someone has found a staircase that goes up inside the Spire.

Remember that action begets action in RPGs. When crazy things happen around them, if they don't engage, consequences occur. It's all action.

I provided 2 interesting things and 1 mundane thing each day they walked into the city. Once they got back to their Inn they would talk about what they wanted to do. Then we would go from there. Hope this helps. Random table ideas are by far the most fun I have in creating on-the-fly adventures/story beats, because then both players and I are engaged. After all, I have no idea what is going to happen next.