The_acrobat
Rock n' Roll Doggie VIP PASS
U2 can do this in big markets like New York, Boston, Bay Area, Los Angeles, Philly.. But not in places like Texas, Arizona, Ohio, Michigan etc This is the main problem today: they can fill 2-3 stadiums in NY or Boston but maybe they can't fill a single date stadium in Cleveland.
On the other hand, this is a list of cities/state in which U2 can sellout an stadium easily:
-NY/East Rutherford (3 nights)
-Philly
-DC
-Boston (2-3 nights)
-Hartford? (small stadium)
-Buffalo?
-Chicago (2 nights)
-Los Angeles
-SF/Oakland
-Utah?
-Atlanta
-Denver
Plus Vancouver, Toronto (2 nights), Montreal and even Edmonton.
Vox
There are a lot of medium sized stadiums in the US that they could do. For example, Crew Stadium in Columbus holds about 25-30,000-ish. Saw DMB there last summer, not a bad venue.
It all depends on the US economy in 2009. It won't be as good as it was in 2005. That might have some effect on potential stadium dates or multiple shows in places like Detroit.