As to why Order of the Phoenix, well the cinema is doing a special rerun of all the Harry Potter films in preparation for Deathly Hallows part 2. Order of the Phoenix (or more accurately the final challenge in Goblet of Fire) is when the films stopped getting progressively more appalling and began to be awesome.
I'm very tempted to go to the midnight showing of Deathly Hallows part 2 on Thursday/Friday, just because I can :)