Originally Posted by EvilMike

Mega Megatropolis is a TSF tileset, but there's a stripped down version available for 1.23. It's not the easiest tileset to use: it's very big and intimidating. But it probably suits what you are looking for: it's bright, versatile, and colourful. And if you want claustrophobic, the tileset comes with plenty of material you can use to make tunnels.

I can't think of any other tileset that can really fill in the niche you are describing. There are plenty of tilesets that can be used for an "urban" feel, but I think the one I described is the best for what you want.