This troper can't figure out why Liu Bei would ever go to anyone else's banquets, considering that he once had two bandit leaders ambushed and killed at one — a strangely common practice, it seems. Worse yet, he manages to go through one such assassination-disguised-as-banquet as the victim set up by Zhou Yu (prevented by Guan Yu's presence intimidating Zhou Yu into not giving the kill signal) and only hears about it from Zhuge Liang after he's left.
Also, banquets were commonly political. It would be politically bad manners to decline them.
Chi Bi (or the Red Cliffs as it's evidently known outside of Dynasty Warriors) seems like such a weird Out-of-Character Moment for Cao Cao. He goes from teaching Yuan Shao that numbers won't make up for inferior strategy in combat to being taught basically the same lesson from Zhou Yu. What's up with that?
It's hard not to bask in the glory of a million man army and believe that you can rest safely in the safety of numbers and experience.
He also basically made the same mistake Napoleon would: he underestimated just how badly an army is weakened by unfamiliar climate and fatigue. His army was made up of Northerners, who were unused to the warm weather and had never been on a ship before. This combined with tropical diseases (against which they had no immunity) and weariness due to the long campaign meant his army was at only a tiny fraction of its effective strength. Had he taken steps to counteract these factors, things might not have gone so badly for him.
As importantly, Zhou Yu took action against the steps that Cao Cao did attempt to counteract these weaknesses, such as his Feed the Mole plot to get Cao Cao's "local admirals" executed, while the entire "chain the ships" plot was a reaction to the unfamiliarity of Cao Cao's northern troops with naval warfare.
The way I looked at it, Cao Cao sort of made the right moves to counteract his weakness in naval warfare. He even wrote off an enemy fire attack because he knew the winds would only send the fire back onto their own fleet. Honestly, he lost because of the winds blowing in a different direction than he knew they would. Honestly, would you have foresaw that move either?
Uh, a question for the blacksmith who made the Peach Garden trio their weapons: how in the holy moon do you make 'ancient swords'?