Also, book a flight early.
Wife is from ABQ and in-laws still live there. We go back about 1/2 dozen times a year. Food is crazy delicious (try to stop by Sadie's on 4th st.) Been to the Balloon Fiesta several times (been a couple of years since my last one). Awesome experience. Very cool being in the middle of all the balloons as they are inflating them and watching them take off. Some people will even ask you to help. Either hold a tie down line, help launch or you could even volunteer to be on a chase crew. Try to go for more than a couple of days because if they have "inclement" weather the balloons will not fly that day. By inclement, that could just be a mild wind (10-15 MPH). Also, take a morning off and don't go to the Balloon Park but find a location a few miles southwest of the park and watch all the balloons from there. It can get overwhelming trying to see all of the balloons when you are at the park. This way you can get a better view of the balloons. Again, just very cool seeing the sky filled with all of the balloons.