Personally I can't stand region tags, but clearly they have wide spread appeal for organizing code, so I want to test the temperature of the water for other MS developer's take on this idea.
My personal feeling is that any sort of silly trick to simplify code only acts to encourage terrible coding behavior, like lack of cohesion, unclear intention and poor or incomplete coding standards.
One programmer told me that code regions helped encourage coding standards by making it clear where another programmer should put his or her contributions.
But, to be blunt, this sounds like a load of horse manure to me. If you have a standard, it is the programmer's job to understand what that standard is... you should't need to define it in every single class file.
And, nothing is more annoying than having all of your code collapsed when you open a file. I know that cntrl + M, L will open everything up, but then you have the hideous "hash region definition" open and closing lines to read.
They're just irritating.
My most stead fast coding philosophy is that all programmer should strive to create clear, concise and cohesive code. Region tags just serve to create noise and redundant intentions.
Region tags would be moot in a well thought out and intentioned class.
The only place they seem to make sense to me, is in automatically generated code, because you should never have to read that outside of personal curiosity.
