I know another mapping question...

My situation:

webserver path /htdocs --> 'www.site1.com'
webserver path /htdocs/site2 --> 'www.site2.com'
webserver path /htdocs/site3 --> 'www.site3.com'
webserver path /htdocs/authfiles --> common file to all three sites/project listed above
webserver path /htdocs/libraries --> common file to all three sites/projects listed above

current local paths
c:\sites\site1
c:\sites\site2
c:\sites\site3
c:\sites\authfiles
c:\sites\libraries


So What would you do?
OPTIONS:
1. Create all my projects with the addition mapping and not have the common files show up in the project. I would like to have access to the files so this is not my favorite option.
2. Create three projects plus a project for the libraries and authfiles and then have to change the URL in authfiles Project and libraries project based on if I'm working on 'www.site1.com' vs 'www.site2.com', etc
3. Change my setup locally so that the common files are duplicated in each project.
ei: 'www.site1.com'
local = c:\site1\html
local share libs = c:\site1\libraries and c:\site2\libraries and c:\site3\libraries
local share auth c:\site1\authfiles and c:\site2\authfiles and c:\site3\authfiles
4. Create 3 projects but the have the local site root at c:\sites\ No URL on Project tab but create all in the mapping tab.
Problem is then the files showing in each project are really from all projects and you have to remember which files you
really need to modify.

I'm just trying to figure out what would be best. All the examples I've seen are for 1 project sharing 1-2 library. I have mulitple projects, multiple urls because they are all aliases, all sharing common files.
And it's not three sites It more like 9 sites so my option 4 gets really messy looking and not ideal.
I'm unwilling to change my local set either if someone has a better way of doing this.

Suggestions?

Thanks

Seems 2nd way is the cheapest one
no duplications.
But I'm not sure why you would need two more projects -- for htdocs/authfiles and for htdocs/libraries.
Why don't you add them as additional directories to all three projects?