How do other stadium acts stack up in terms of the 'blue dot' availability? (i.e., Coldplay, Guns n' Roses, etc.)
I saw both Guns N Roses and Coldplay last year, both in Pittsburgh. Coldplay played the hockey arena, selling out with somewhere between 14,000-15,000 tickets, grossing a little bit over $1.6 million. Guns N Roses played Heinz Field, where U2 will be in June (and, where they also played in 2011 news the end of the 360° Tour). According to stats posted on the Wikipedia page for the tour, there were exactly 3,000 unsold tickets (39,120 out of an available 42,120), still grossing close to $4 million. In 2015, The Rolling Stones played the same stadium, selling all available tickets (over 54,000), grossing over $9 million. U2 also soldout there in 2011, selling a similar amount of tickets, closer to 56,000, grossing a bit over $5 million.
As I recall, that U2 was also slow to sellout. IMO, with Cleveland only being 2 hours away, and with barely a month between the two shows, replete with their being smaller population centers when compared to many of the other areas where they're booked, is largely why it's been a slow sell. When all is said and done, though, I'm confident that it'll either be a sellout crowd, or damn close (like with Guns N Roses last year).