Here's the Albuquerque Balloon Fiesta site:
Albuquerque Balloon FiestaWe went this past October with a group of 30 and stayed from opening day to the day after closing. We all volunteered for various crews - can sign up once you're there. It was a blast to help in launching the balloons and we also got a free ride for our efforts. We stayed on the Fiesta grounds in the dry camping area. The free shuttle bus stopped by our RVs and we were on the grounds in 10 minutes.
I would highly recommend staying on the grounds rather than a local RV park. The traffic coming into the Fiesta is a nightmare.