medium size hotel chain, currently using an agency that has build some
of the infrastructure using ColdFusion are looking for advice on
whether Coldfusion is the way to go, versus .NET and Java.

I find problems with Coldfusion and i need to make a case against it
(in favour of MS.NET or Java). or alternatively, pro Cold Fusion. The
company needs a highly flexible software environment, webservices,
connectivity into SAP, costs are also an issue, scalability etc.

I have been developing ColdFusion applications for several years and I
don't think that there are any issues with the platform itself.  I
believe that if you have experienced developers then you will be ok
with any of the platforms CF, .NET or Java.  If the developers that
you are working with are primarily experienced in CF then I would
recommend using CF.  If they are also experienced with Java I would
still recommend CF, because CF is written as a J2EE application.  This
allows developers to use CF as a "Rapid Application Developent tool"
to get things up and runninq quickly and still leverage Java if they
find that something they need is not built directly in to CF.  CF has
many features that help to get applications up and running quickly as
well as the extensibility to add features when the need arises.

If you are concerned about the scalability of ColdFusion, I don't
think it is an issue if the application is written properly. 
ColdFusion does well in a load balanced environment using sticky
sessions or clustering if needed.  The same also applies to the other
platforms although I believe .NET or Java will be more expensive to
develop.  Once again this depends on the developer.  Generally if a
developer is experienced in the platform they should be able to build
a stable/scalable application.  There are also frameworks such as
fusebox, mach-ii, model-glue, and coldSpring for CF that can help to
organize the content and application structure.  Using a framework is
not a requirement, but it is a good starting point of a well
structured application.

1. Stick with what the developers know.  A poorly written Java or .net
app will not outperform a well designed CF app and vice versa.
2. If you have developers who are more experienced with Java or .net
and the applilcation needs a rewrite then it might be a time to
switch, but don't expect the platform to make the difference.  The
design of the application is more important.
3. A scalable applilcation requires modularity.  ColdFusion
applications should be made modular by using cfc'c, custom tags, and
cfmodules.  Using a framework(fusebox,model-glue,mach-ii,coldspring)
gives a good structure to build on.  I recommend usinig model-glue
with coldspring.   Coldspring is a port of a popular java framework
that works very well in CF.

www.model-glue.com
www.coldspring.org
www.mach-ii.com
www.fusebox.org

hope that helps