I assumed Gregory was asking about nested classes in the context of wrapping them in regions..

I think there are good some good reasons to use nested classes themselves. e.g:
(a) Where the nested class is closely tied to the outer class - i.e. has no use elsewhere. The classic example usually given for this is a nested class which implements IEnumerator within an IEnumerable which is then returned from the outer GetEnumerator().
(b) Sometimes it is useful to be able to take advantage of the fact that the nested class has access to the private variables of the outer class....

>I am sure there is some case for nested classes, but I can't think of any and I don't do it. Structures yes, and if I could think of a good reason to nest a class I suppose I would consider it. Probably won't happen. Large array initializations? I don't have any thoughts about. Sounds like stub data to me.
>
>>Good point about the refactoring
>>
>>What would be your take (gustibus) with
>>
>>- large array initializations
>>
>>- nested classes
>>
>>__
>>
>>
>>>Yes, C sharp has partial class files but I do not use them for general classes. I do not like looking in partial classes to find the code, I like it organized in a single code file for a class. However, I also keep my code limited in a class to what the class should be responsible for and refactor out any base code, etc. I do not have classes that contain thousands of lines of code. I use regions only to collapse specific areas like Viv mentioned that allows me to scroll much easier when needed or to just view some methods or ??.
>>>
>>>Thanks
>>>
>>>>Tim,
>>>>
>>>>I sometimes use several files to split
>>>>
>>>>>In my opinion the #region is goog organization of code and I use much the same as Viv. Using ReSharper helps navigate code but sometimes for instance if I have many properties in a class, collapsing the region around the properties makes the file more manageable to wonder through. I don't view it as hiding code, but rather just part of organizing.
>>>>>Just another view point.
>>>>>Timothy
>>>>>