You guys are hitting on a lot of fairly decent picks.
TJ Ribs off I-10 at Acadian (good ribs, good brisket - totally LSU atmosphere)
Izzo's burritos - I like them if you want a azz load of cheap mexican food
George's or Ivar's under I-10 are not bad po-boy/sandwich spots
Chimes at the gates of LSU - good food and tremendous beer choices
Walk-ons - I just do not like their food, but it is close to the ballgame
Past-time - near the riverboat casinos and a few miles from Alex Box - run down pizza joint - some people love their pizza - I do not
Mellow Mushroom is pretty good pizza
Parrains on Perkins (not too far from George's and Ivar's) is about as close to good Cajun seafood as is available in BR.
Superior Grill - Government Street - Pretty good fajitas... don't like a lot of other menu selections.
There are some other good eateries (Italian, etc) but they are not pre and post ballgame joints.
My recommendation would go to Chimes (food variety and beer), Parrains (seafood), George's (po-boy), Voodoo (barbeque), and Izzo's (big fat tasty made to order burrito).