I didn't go last year but went in '14; a GA ticket gets you access to the whole infield. Almost all of the viewing mounds give a good look at several corners, and each has its' own advantages. You can get a general idea of the corners you can see from the track map on IMS' website, so my advice if you want a "base of operations" is to pick the one that looks best to you to set up your stuff (people were pretty good about watching blankets, etc. if you ask), but I highly recommend wandering around and checking out the vantage points all over the property. As an added bonus they set up Jumbotrons across from all the mounds so you can catch all the action without too much trouble.
The permanent Jumbotrons face the outer stands for the most part but the funniest thing I saw in '14 was a bunch of people lying on the backside of the mound inside roadcourse Turn 1 watching the big screen while the race was going on over the hill behind them....