Never been but last time I was considering a concert they offered reserved parking at the same time as buying the tickets. Have you looked on Ticketmaster for your dates?
More info about parking here: http://www.amwaycenter.com/directions
The Who is playing there while we are there in Nov but I only know one of their songs (Pinball Wizard)
Hi, we went to a game in the Amway back in 2010 parking was very easy and well sign posted (because we were worried before hand that we would struggle!) but as you came off the freeway there were signs for parking right by the Amway and there were security guards etc there and it was only a few minutes walk to stadium.