I would have to agree with Monovoa. Most of my AotD awards have come from heavily defended enemy cities. The key is to break down the wall with your revolt attack (catapults) and keep quaking and sending catapults in waves. Your land nukes and LS nukes will clear all incoming support as long as you have the firepower to deliver before your CS lands. Most importantly, you get the best value out of your offense, yielding more ABP than the enemy's DBP. It's a great tactic.
Also in the past when there was a greater presence of enemy cities in our central oceans, I would build massive land nukes on islands shared with enemies and choose a day to launch them all. Some Lost Boys and NSPG players may remember this
Edit: AotD awards have been restored
How many AotD awards do you have? I'm very curious to see how many the top 10 attackers have. I'm at 19 currently.