Colleen,
When I read your note, all the things you mentioned seemed (to me) much
more like subthemes, not primary.  Maybe if you did something like
"money: form and formal" (my title) then you could use the exhibit to
explore the ideas of trade, economics, leisure time, surplus, devel. of
class structure, barter, etc., all of which could/would incorporate all
the areas you mention and, i think, a few more  [anthropology background
comes to the fore].

My questions to your planning group would include:
        what is your planned audience
        "     "   "  space/duration of exhibit/security of exhibit space
        "     "   "  planning time
        "     "   "  projected budget
        "     artifacts (or whatever) do you have/have access to tell your
story

it may well be you already know those answers, but if not, maybe they'll
help give your exhibit some orientation.

Good luck,
Linn

Colleen wrote: <multiple snips >
 We are trying to develop an exhibit proposal for "Money."
>
> We have many good ideas, but have been stumped nailing down a sub theme.

> What we're stuck on is what kind of a thing is a sub theme.
> Could anyone offer any advice as to what a sub theme should be, and maybe
> examples from other shows about themes and sub themes.

> Colleen Sharpe