Here's the latest and greatest. I'd say it's on the cusp of completion.
Ended up compositing the background in separate. I had no idea After Effects had such great compositing tools. The Luminosity Lens Blur saved the day when it came to selling the depth of field. I ended doing a few touch ups in Photoshop, including some additional blur where my DoF map fell short and some color highlights on the petals.
AO map came out much darker than I wanted, and so that was tweaked before going into AfterEffects as well. Also some minor color correction with the Curves Editor.
If anyone has any more suggestions or sees something I missed, please do tell.
Also, I'm not sure if I should put the reference photo in my portfolio to show what I was aiming for, or if it would better leaving it out.. On one side, it shows how close I was able to get, and on the other it also shows where I may have fallen short. Anyone thoughts?