In January I started a little fun project to continue learning C#. Using MOGRE (Managed Ogre3D) and WinForms I started a little editor. It's really at a very, very early state and currently I am too busy to continue working on it, but I have to say, I enjoyed working on it so far.
C# and WinForms make things really a lot easier (I don't like MFC!). And I have touched only the top of the Iceberg so far. C++ is powerful and gives a lot of freedom. Lots of freedom = lots of choices = not always easy to make a choice. I enjoy having some "standard solutions" in C#, like delegates. Built-In Introspection/Reflection/RTTI is also really, really, really cool!
As everything is also of type "object, I believe that node-based editors/programming should be much easier/faster to realize using Dot.Net/C#. Sure, if you need to be portable and if you have to squeeze out the most of the hardware, C++ is the choice. If you do some PC-only Sims or Viz and you don't mind wasting some CPU power, why not? There are not yet many 3D render engines available, but they start to appear (i.e. XNA based).
At work, I decided to implement a (non 3d) project in C#. There are a bunch of asynchonic ways of doing things, and for me it's not so transparent yet (what happens in what thread, what is threadsafe especially when things get layered). But I guess it's a matter of learning and understanding the framework.
Most of the time I am using Visual Studio 2008 Express and for a free tool it's impressive. It does now do lots of things too that previously was only possible using 3rd party Add-Ons like VisualAssist. Something I am missing is to be able to filter the intellisense drop-down list by type (Property/Event/Method). VisualAssist has some filtering buttons at the bottom and it's useful.