I've actually been quite content playing some Domination and integrating Academy cards into my current spell books. I'm REALLY looking forward to Paladin VS Siren. Bout two expansions a year is just fine by me.
Agree on the Domination side. We have moved to this format as our primary play mode and found the need to modify spellbooks and strategies for the scenarios and victory conditions.
Laddinfance, as far as new content it might be fun to add a section to the Battlegrounds part of the website where AW can publish new scenarios for players. Perhaps a 6-player free for all or scenarios for combining two expansions together. If two players have the expansion we now have 40 tiles to create maps and dozens of Ssalks. Recently we thought about making all the standard scenarios tougher by replacing Ssalks with their bigger brothers. 
That doesn't necessarily make it tougher, that just means they take longer to kill and increases the length of the game.
40 tiles is a lot. How are you going to be able to reach your cards on a 40 tile arena? I mean, it would be really fun if you could, but I still haven't figured out how to do it without some sort of technology or special rules to make it no longer a genuine super-sized arena.
I tried to make a league of legends format once, and it didn't quite come out how I wanted it to. It would be cool if there were some way to make 3v3 and 5v5 mage wars arena shorter and more streamlined. Sharing turns with your team doesn't seem to be enough considering how many creatures they can summon. Maybe share spellbook points and "purchase" spells for your mage throughout the game, like in LoL?
