I just wanted to confirm that you meant "#regions" and not class layout in general.
I am surprised no one has mentioned to avoid using regions. I understand the OP wants to take a poll on laying out regions, but I'd like to raise an alternative view point.
I avoid regions. I like to see the code I am working with. If you find it difficult to find what you are looking for then use code folding and group similar class constructs together.
Why do I hate regions? CTRL+M,L and CTRL+M,O will toggle code folding. However, when collapsing it hides the entire region. I only need to collapse methods/properties/comments.
If there are too many regions maybe its a code smell and your class is doing too much work. Jeff Atwood provides a good post on regions which is worth a read.
My favourite quote on #regions:
No, I will not use #regions. And no, I DO NOT NEGOTIATE WITH TERRORISTS. Shut up.
That being said, I know many programmers insist on using them. This question is a subjective. I'd just thought I would offer an alternative.