Jesse, not sure what all that might be, but I assume (maybe incorrectly) depending on the medium they print on things such as contrast, saturation and sharpness might need to be optimized.
Greg, I use White Wall (whitewall. com). I do not want them to apply any changes to my files whatsoever. This means that I do not select print optimization. I also do not use their print service, which adds sharpening (I forget what it is called).
Depending on the type of final output, I use Fuji Crystal Glossy (color) or Ilford Black and White Glossy for large prints mounted behind acrylic, or Hahnemühle Photo Rag for unmounted prints.
It took several iterations of test prints to nail down the process. Now I know what I am going to receive when I send them a file. The quality control has been very good. I have had the same files printed on multiple occasions separated by several months, and they were virtually the same.
Unlike the darkroom, I have no interest in maintaining equipment for digital printing.