ok. both of the things you suggest seem like good ideas. on the second point, it would seem that what you what is to be able to define a separate blank workbook template for each series of workbooks (which i think means per parent container). Somehow as part of the initial step of adding a workbook series to that container you pick which template to use.

An alternative would be to create some number of site-wide templates. when you create a workbook, you pick the type of workbook you create, like what happens when you create a folder. this would mean that within a container different workbooks use different templates.

One goal of 10.3 involves creating the 'make workbook' API. Although workbook templates are not part of 10.3, if they are added, when calling the API we'd need to be able to specify what template is used to create the workbook. not sure if it needs any upfront consideration or not.