Rules to decide which wonder side (A or B) to play in 7 Wonders?
This is a tricky one. The rulebook makes seems to specify option #3 pretty specifically:


  Shuffle the 7 Wonder cards, face down, and hand one to each player. The card and its facing determine the Wonders board given to each player, as well as the side to be used during the game.


However, when I demoed the Leaders expansion from Asmodee at a convention, option #4 was used; the cards were dealt randomly but players were allowed to choose their own sides. This was the first I had seen this rule, but it seemed to work well and I immediately started using it in casual games as well. Not only do players get to choose the board they like better, but there's no worry about making sure to maintain the orientation on the Wonder card when revealing it. I encountered the same rule at GenCon 2012, when I played (with little success, sadly) in a tournament.