In Civ4 I would improve the key points around a city to be how I wanted them and then normally stick a worker in to the mode that would improve just that city, with workers do not remove forests and workers do not touch old improvements both enabled in the global options. I'd occasionally just stick a worker on to improve city around one I've captured that I've captured and am not interested in micromanaging.
All three of these options seem to be missing from Civ 5.
I don't want to automate my workers to work globally, as I hate them touching the stuff I've actually taken the time to configure myself, they remove too many forests for my liking, and I don't like them walking about the map all over the place (for safety and because I like my workers spread across the nation, not all bunched up irrigating one city).
So, are these options available anywhere in Civ 5?
If not, can I emulate them at all?
On 22nd Oct 2010 the game was patched to version
184.108.40.206, which has added a option to the ingame menus so force workers to not change manually created improvements. I believe that they will still overwrite improvements previously created by automated workers.