Cre8tvlwyr...I used a dark olive green background on mine. You are right, you do have to be careful of your leaf color choices. But I think you would have plenty of leeway in greens that will still pop.
As far as the fabs from CT...I recently ordered a "stack" of the batiks to try them. I think they are a bit thinnner than some of the other batiks I've used like the Fossil Ferns or Bernatex, but they are very nice to use for the applique pieces. I think I've heard several people doing the AOTH talking about using Mirage for background. As you read through the thread, you'll see some comments about that.
Now..I have to go check out the links you gave on the guilds. Edditted to say...I DID go look and both quilts are lovely! I'd love to see your Amelia's garden!