This seems so stupid, I have to believe I have either overlooked something or I'm doing something wrong...
(Free Sketchup 8.0.16845 on a Mac -- current version)
If I open an existing sketchup file, and work on it, and then decide to save it under a different name, I click "File -> SaveAs" then BY DEFAULT Sketchup will NOT offer me the current directory. No, rather it offers to save the file in a DIFFERENT directory.
And I have not yet figured out the pattern for WHERE it decides to suggest I stick that file.
This drives me NUTS. Regularly I will save a file quickly, and then come back later and find that it is NOT where I thought it was, but in some other folder on my mac.