We were in the AK parade once, and asked another time and declined so some one else could ahve a chance.
At the AK they find you at Donald's Breakfast. They specifically look for families/couples/groups of 2-4 people. Generally speaking they want the kids to be at least school aged (absolutely no infants or toddlers). They seem to look for a variety of people from different areas, different ethnic groups, etc. They bypassed larger groups and families.
A few things I specifically noticed were:
They looked for people who were nicely dressed (I didn't say expensive, I said nice.) In other words no cut off's, no tanks, kids who had their hair brushed and weren't wearing stained clothing. Both times we were asked DH was in a golf shirt and nicer shorts, DS was in a Disney Tee and shorts, and I was in a sleeveless collared blouse and shorts. In other words dressed just shy of Disney's version of business casual.
As we were all backstage getting ready for the parade I noticed everyone was pretty much dressed like we were. There were no wife beaters, tramp stamps, or visible floss.
They seemed to want people who were laughing but not obnoxious, and having loads of fun. It was obvious they didn't want people who looked cranky, tired already at breakfast, or like they weren't having a blast.
None of the families chosen were shy wall flowers. They were people who would love to sit on the float and wave at people for half and hour.
I want to think there were five families in our prade. Us (DS who was 16ish, DH, and myself), a couple from the UK and their daughter who looked about 10, a honeymoon couple, three women visiting together who were late 40's-mid 50's, and a single mom with her two kids who were probably 8 & 12.
Let me know if you have any questions.
Anne