I'm doing background research for a freelance online article about
what really drives companies to move out of or move into a particular
city.
 I'd like to hear from Commercial Real Estate firms as well as Comtrollers/CFOs.
 My question is this:
 Of these three factors, which are most important when considering
location decisions:

1. General business climate
2. Landlord improvements and amenities
3. City-funded initiatives and incentives

Without being funny, the location that is most personally convenient for the CEO

I think it might be Robert Townsend that came up with that one
- although maybe I heard it before

The most extreme case I've seen was a US company who located their
European head office in Munich, when most of their operation was in
the UK.

When the European (German) CEO was caught with his hands in the till,
there was a rapid move of HQ - from Munich to the UK.

Without joking, I would explore that angle, it makes a lot of sense.

Well, the article I'm writing is due to an impending p****ing match
between myself and a local City offial.
  A reader of a locally oriented online forum called my city's recent
high vacancy rate "embarassing" and took City leaders to task
wondering why it was so high and what was done to lower it.
  I responded that the vacancy rates were high because of forces very
much beyond the city's control - late 80s/early 90s recession
primarily -  but IBM, Prodigy and other big firms shedding workers
(and emptying out entire buildings) didn't help either.  I also
insisted that the bounceback in occupancy was largely due to an
improved economy, and owners of those empty buildings gussying them up
and repurposing for multi-tenant use.
  A city official then took me to task on that same forum, saying I
have no idea what I'm talking about, that a lot of the re-tenanting is
because of proactive effort on behalf of City leaders.
  I still say, "hogwash" and I'm trying to find out for myself what
really drives these sorts of decisions.
  I'm trying to buttress my argument with general background
information, as well as situations that pertain specifically to the
city in which I live.
  I am also willing to eat a little crow - if my findings are that a
city, particularly mine, can influence prospective firms to move in,
I'll put that in my story, too.

Interesting.

My knowledge is mainly from the UK.

It has been noted that Government grants to companies to induce them
to locate in a specific area, tends to attract capital intensive
companies, so there is little 'bang for the buck' in terms of demand
for labour.

Local Government can certainly lose companies, one case is the Dyson
factory at Malmsebury near Swindon, where he wanted to expand the
existing factory, but was refused planning permission (zoning) so he
moved all production to Malaysia.

Other examples in the UK and USA are out of town shopping malls that
devastate the local retail infrastructure.

My view is that local Government is more likely to have a negative
effect on employment and economic activity.

It would be interesting getting that city official to itemize the
'proactive effort on behalf of City leaders'
- he will probably demolish his own case

I agree with Frde's last sentence.  If the city's pro-active measures
were being successful, they would probably be generally known and have
been found logically useful.  OF course, even if they were, they would
not necessarily have a significant impact, since overriding economic
conditions cannot be countered by local measures.

Similarly, if the city official had facts to support his claim, he
probably would have mentioened them, especially since the forum was a
local one on which he could expect voter viewing and participation.

Just ask him to justifiy his claim with some facts:  the measures and
the resulting increase in re-tenanting  - and then do your homework.

Good luck.