Were I in a theater it would be with my wife and son. Now my son is a good sized 14 year old kid but still just a kid and my wife is a 14 year army vetran but still my number 1,2 &3 thoughts would be getting them out of harms way period. If I was trapped or cornered and all I had to fight with was a bag of popcorn to give my family a split second to make their escape you better believe I would do it. But to think that you are going to do more than buy them some time with your life against the much better armed opponent (AR, 12 ga. shotgun, and 2 semi auto pistols) who doesn't have to worry about hurting innocent bystanders is little more than wishful thinking.
Think about how many "What is the best defense arsenal I can have to protect myself" scenarios have come across these forums. I have seen reccomendations for the AR; excellent weapons in the proper hands, the venerable 12 ga. shotgun; always a comforting thing to have, and a good quality semi-auto handgun, hell this nutjob had them ALL.
I can't even imagine the situation to my satisfaction, a dark crowded theater, lots of noise (besides the gunfire), flickering lights from the movie, a lunatic shooting at everything that moved, and dozens of people suddenly realizing the no-win situaion and trying to gang rush the exits, its a miracle that more people werent killed. You simply can't "win" every scenario, imagine trying to practice shooting in such a situation for fun, now try to imagine it where if you miss or fail you die.
BTW my daughter lives 70 miles from Aurora CO and yes for a few minutes after I heard about it my blood froze until a quick text and reply allowed my heart to beat again.