Somewhere Back in Time tour. 45 days, 23 shows. See Flight 666 for details (and some excellent footage from 16 of those shows.)
Also awesome: Bruce Dickinson flew the tour plane on that tour and is a commercial airliner pilot. Yes, he has two of the most stressful jobs in the world.
Iron Maiden in 2008 playing in India, 30,000 people packed the stadium for the first big metal band to ever play in the 2nd most populated country in the world. History was made when the devil horns were thrown up in the whole crowd rocked out.
Live After Death. Full Stop.
Any time Eddie makes an appearance during one of their shows.
Let's go to the point: anytime Iron Maiden appears on a stage is a CMOA. The band is thrice-distilled, pure awesome. Want proof? Watch Flight 666. There is a priest out there, who bases his sermons on their lyrics.
In 2006, at the Nassau Coliseum (Uniondale, NY) gig of the A Matter of Life and Death World tour, some dumbass thought it would be a good idea to bring a sign that read "Play Classics!" for a tour where Maiden would play the eponymous album. During "For the Greater Good of God", Btuce finally noticed the dickhead with the sign and tore it apart. While on the bootleg all you can see is Bruce having the dick hand him the sign, this video allows you to see the badassery from the front row.
On that note, any time Bruce yells at a dickhead in the audience.
Nicko once played for Pat Travers in the seventies, and admits to hating it to the point where "I wouldn't stop to piss on him!". At the 2009 premiere of Flight 666 in Rio, a dumbass yank in the audience asked Nicko a question about Pat Travers. Nicko lashed out against him and had him removed from the cinema.
Similarly enough, he ran a security guard over in a Dallas parking lot in 2003 prior to a show in Dallas. Which inspired a bootleg called "Running you over!"