I created a new Site Workspace template per the instructions from MSDN- Create a Empty New Project Workspace and used these sections below in the instructions. I had a issue with using a blank template to start and not being able to publish and create a new workspace that Daniel was able to resolve for me. Now I have my new site template created, it is promoted to global status and I am at the point to select the default workspace template in PWA.
When I got to Procedure 5: I am not able to select this new workspace template in the Default Project Workspace Template drop down box because it does not show up as one of the template selections to pick in the Default Workspace Properties section in the Project Workspace Provisioning Settings. Do you know why? Has anyone else had this problem?
Procedure 2: To create an empty new project workspace:
then Procedure 3: To create a project workspace site template:
then Procedure 4: To promote a project workspace template to global status:
then Procedure 5: To select the default workspace template in Project Web Access:
In my EPM2007 deployment I have used the following as a guide numerous times without any problem, not sure if it indicates any difference with the process you have been following, but hope it helps: