Allow leaders to choose the size of the war, and the War roster.
This is a big one, and I really hope it hasn't been ruled out because it would really make the game that bit better.
As a leader of a clan of 42 people, with 48 war wins, it gets really frustrating trying to organise 40 vs 40 wars and making sure everyone not only attacks, but attacks well, and then trying to fill every base with wizards and dragons on top of that gets a bit hectic.
I much prefer the small 20 v 20 wars, but at the same time I don't want to kick any members as they have all earned their spot and it would drop us down too much trophies.
So, what if, before the leader searches for a war, not only can he pick the size of the war (10 v 10, 40 v 40 etc.), but they can pick their own roster for the war? That way it would make people work harder to try and get on the team (sports anyone?) and it would make life a bit easier for a clan like ours who prefers the smaller wars. It would also bring no harm to the people who like all-out 50 vs 50 wars.
It would make my day, my year, my CoC life, if an update along these lines was released