mdmomof7, do you live in Washington DC?
Yes, I think it might not be possible to get a ticket, even if we shood outside the auditorium holding a 'ticket wanted' sign.

On the 360 tour it was really easy to get tickets like that (because 360 is in a stadium), but since this is in an auditorium with limited seating, we might not be able to get (buy an overpriced) ticket even then.
If you're going to hang around outside, you could look for the auditorium back doors/ stage doors, so maybe you could see Bono coming in and leaving!
