The important ingredients, so often overlooked, include mixed-use zoning and public spaces. If all you have are a bunch of condo towers abutting each other, you're almost guaranteed a dead high-density area.
Once you start mixing things up, though, it gets much better. Add some restaurants and shops and other businesses on the ground floors of the condo towers (even better, mix in a few two-to-three-story retail centers), and some small parks, squares, and other public areas, and the density can be leveraged to create a thriving street-level area.
Once you start mixing things up, though, it gets much better. Add some restaurants and shops and other businesses on the ground floors of the condo towers (even better, mix in a few two-to-three-story retail centers), and some small parks, squares, and other public areas, and the density can be leveraged to create a thriving street-level area.