are the A3's going to require stands for support ? When the choice is front bookshelf speakers on stands, or floorstanding speakers - I would choose the floorstanders. If it were my choice, I would go with A7's or A9's, because you stated it is a big room with high ceilings. It takes a lot of "cone area" to push enough sound to fill a large volume room. Esthetics aside, large room = larger, or more, speakers.
After you are set up, you may find you need a second subwoofer as well.