After reading nunzia's post and starshine514's post, I was curious and signed on to my PhotoPass account to see exactly which stock photos they gave me.
I guess that the more PhotoPass pictures you take around both parks, and based on the specific areas in which you have those shots taken, they will give you more bonus stock pictures.
On this past holiday trip, I did not have nearly as many PP pictures taken as I have had taken in other years - and they only gave me 9 bonus stock pictures! So take more PP pictures all over the place and you will get more bonus pics!
Of the 9 bonus characters I was given, this is the breakdown:
1. Three shots of the Fab Five (Mickey, Minnie, Donald, Pluto and Goofy) in front of the Mickey floral at the entrance to DL. In each one the poses are slightly different;
2. One picture of Mickey by himself in front of the Mickey floral;
3. One picture of Mickey & Minnie together in front of the Mickey floral;
4. Two pictures of Mickey and Minnie at the train. In one of them they are both looking at the camera. In my favorite shot, Mickey and Minnie are gazing at each other, holding hands, and the steam from the train is adding atmosphere;
5. One adorable photo of Mickey looking at Partners. The Castle is in the background, of course, and there are some gorgeous pink-ish flowers surrounding Partners. Mickey is standing in the background, to the right, looking up at the statue; and
6. One photo of Minnie standing behind the gorgeous pink-ish flowers mentioned above - the flowers are in the foreground and Minnie is in the background. This was taken near Partners but you don't see Partners in it.
I could have sworn they had given me a third picture from around the Hub/Partners, but if it was there a few days ago it is gone now!
Oddly, I had several PhotoPass photos taken around DCA - by the waterfall, with Duffy, by the Christmas tree, on the bridge leading into the Paradise Pier area of DCA, etc. - and I did not get one single bonus stock photo from DCA! Weird! I guess I just didn't go to the right spot for them to add on some DCA pictures.