I'm a GIS specialist working in the energy sector, if you're looking at enterprise level solutions then ESRI are the Microsoft of the GIS world, there really is no one else who comes close to offering such a complete package.
We use 9.3 Desktop, 3xArcSDE DB sitting on Oracle with replication, ArcGIS Server 9.3, 9.3 Image Server and a whole host of extensions.
I'm currently developing ArcGIS Server web apps using the ESRI API for the Adobe Flex framework, it really is the future of web GIS and you'll see some incredible products coming out soon that use these new APIs (Flex, Javascript, Silverlight).
I used to work for a central London local authority planning department and they have a lot of good examples of zonal planning for things such as tall building development, it's almost down to an art form and is very detailed.
Drop me an e-mail in my trust if i can help any further.