Congratulations! I am so very happy to hear that you've finally been approved! What wonderful news.
I have tried a few different spots for both my Dex and OmniPod, but have always (for the past few years now) gravitated to using my abdomen for my Dex and the back of my upper arm for my OmniPod. I inject Symlin too, into my abdomen, on the opposite side of my Dex. Symlin needs to be injected at least two inches from insulin, so I play it safe this way.
I'm glad you asked this question because I need to pay better attention to rotations than I know I have. I move from side to side, but I have never paid much attention to placement on that side, such as doing what's been suggested here or something like a "clock rotation" with 12, 3, 6, and 9 points. I might find in a few more years that I'll regret having not done so.
Again, congratulations and thank you for asking such a great question!