I'm also -1 on dicts -- just use a second dict to hold docstings.

Can you elaborate on your proposal for named tuples? Keep in mind that the API is already somewhat complex and should not be expanded lightly.  

Also, the whole point of named tuples is to allow you to assign attribute names that are self-documenting (otherwise, you would just use t[0], t[1], etc).  So, I'm not sure what the benefit would be for overriding the existing, auto-generated docstring which already gives some useful information (i.e. the position index of the attribute).