In theory, according to the AS program guide, you can get 5 miles/dollar. However, nobody on the AS thread seems to be able to do this anymore.
I used to do this, then switched to NWA (offering a similar 5 miles/dollar), then noticed that I stopped getting this in March 03, but also that may be due to me switching around my phone options at that time.
So, in sum up, NW and AS both offered $5/mile for continuing customers (I added this well after the getting my PCS phone) at one time, and may still offer it. According to the AS program guide from the web site, you still get this for plans of $50 or higher a month, but nobody has reported success with this recently.
Good luck!