To clarify Stevie and I are talking about two different Revit tools/ features.
If you are using the Inplace Family option :

This is great for conceptual modelling of buildings and parts of building that may not be easily created using the basic walls floors tools etc. You can then use the model by my face to create quick conceptual models.
However if you want to make some geometry that behaves with a particular family category but you don’t want to make a loadable family then you can use the Model in Place tool. (You can also make a mass family in this way.)
I find this Model in Place family tool useful for placeholder families that may be swapped out later and for additional geometry custom extrusions blends sweeps etc.
I have attached a quick screen cast to show this tool being used. You access all the family editor tools while in the project environment. From your description I think this is the tool you are looking for. Hope this solves your issue.