Suggestions for fun stuff:

• Catastrophe is a super-fun board wipe, especially if you want to go the land destruction/threatened land destruction route. Play of the Game is also maybe a good idea in a multiplayer setting.
• To protect yourself from mean opponents who hate fun, I could suggest Spirit of the Hearth, Leyline of Sanctity, Seht's Tiger...
• More O-Ring effects could be fun, so maybe Admonition Angel could be worth a look.
• Also, in lieu of Moat, maybe Magus of the Moat and, in that same vein, Magus of the Tabernacle could help to ensure that people don't mess with you (too much).
• In terms of Planeswalkers, the only one I can think of that might be useful is Elspeth Tirel, largely because she resets the board quite a bit and provides protection (plus, she's not the huge target that Elspeth, Knight-Errant or Elspeth, Sun's Champion are).