On this topic I am happy to go with the wisdom and overview of more experienced developers of this GREAT framework. The debates in these forums are excellent learning.
My main hiccup with GAE has been the use of bigtable for images and document storage. Thanks to ( a few ) excellent posts and slice on this, I have pieced together a solution ( under test ;-) a plugin to generalise this/more examples would be great. Wish my coding was up to it :-(