One thing I've learned over the years as an "Old School" DM is that you can never have enough random tables. Well, that's not totally true. I don't need 101 Things Found in the Middens (actually, bad example, as I can see my PCs digging through that shit). The thing is, one good set of tables is worth more than a thousand tables that are so esoteric they will rarely, if ever, come into play.
The tables in GM's Miscellany: Urban Dressing II (System Neutral Edition) WILL come into play. Sandbox prep often means lots of basic info but little drilled down. These tables help solve that problem for urban environments.
That's a ton of inspiration in those tables listed above. Hell, the Hooks, Complications and Opportunities could probably keep a campaign going for years with the right group. Here's just a small example:
$12.99 isn't cheap for a PDF, but put this on your tablet for easy reference and you should be as good as gold.
And yes, I'm trying to complete my GM's Miscellany collection. I'd like to try and do some "live" campaign prep at The Tavern as a series of posts using this collection and the D30 series by New Big Dragon.