Comparing my reactions about Hammerfast and Vor Rukoth, it seems I prefer richly detailed over empty.
Hammerfast describes most of the buildings (and the most important inhabitants) in a settlement and gives an overview of the surrounding area. It also includes ideas for a mini-campaign. I thought it was the perfect level of detail to inspired me.
Vor Rukoth describes the ruins of a vast metropolis, giving short overviews of districts and describing a handful locations for each district. Aside from remining me strongly of the old Parlainth box for the Earthdawn rpg, I felt that was too sketchy to make good use of it. While there's a ton of adventure hooks, just like in Hammerfast, I felt I had to do all the work to create a full-fledged adventure from any of them.
The only area sufficiently detailed to get started with minimal work is the starting area outside the city. There's also practically no info on the surrounding area.
Similarly, in the Eberron setting, the party recently traveled to Graywall, the major city in Droaam.
Using just the ECS you get a small paragraph of info. I didn't really feel that was sufficient to describe it properly to the players and have good answers for their questions. My usual tactic to rely on a couple of random tables seemed not to do the place justice - it's a city of monsters, after all!
Luckily in Dragon there had been a backdrop article, detailing the five city districts, pinpointing hot spots and a bunch of npcs. Even without providing a map that was sufficient info to play a session in Graywall and give me some ideas for a side-quest.