Doug,
I am going to have to say, DDog's Apple Rub. My team uses it and I know a few others that do as well and have great results.
As for injecting, we love the DR. Dr. Pepper that is. Make sure it's flat first..
For the mop/baste, the cider vinegar and cider are good, I personally like Snapple due to it's sugar content, but they all work well.
Good luck, try them all and let us know your results..