No, the upgrade thru Orbitz varies a lot. $20 is kinda high really. I saw a sign in the lobby that they give free upgrades to repeat customers who book thru Orbitz, but I like to guarantee the large room in advance if I can get it cheap enough. We paid $7/night to upgrade I think, on an air & hotel package with $200/room discount.
The day we arrived there were three signs to that effect at the front desk, one each for Orbitz, Expedia, and Travelocity. I noticed later in the week there were only two, Orbitz and one of the others (can't remember which).