OK, here are my thoughts on the next step...
If the national media picks up and gives the slightest mention of the banner.. then it is DONE.. no need to fly it again, it would have substantially diminished returns. If there is NO national coverage at all (seems highly unlikely) then I would say it may be worth flying it again.
If we do get national coverage (even a little) then I think you go with a billboard if it is economically feasible. If not, then I suggest looking into expanding the online reach and other grassroots efforts like a concessions boycott or whatnot.