Casting plane shift by itself should be sufficient. The spell doesn't require any planar connections to work, just that you have the focus for your destination plane.
That said, there are apparently no special consequences for combining plane shift with rope trick. The latter spell description states, "the window is present on the Material plane," but that's clearly working from the assumption that you were on the Material plane yourself when you cast it. AFAICT, if you're totally stuck on a particular plane, no manner of finagling with rope trick will let you escape.
However, if you have a portable hole and a bag of holding, there's your way out. Gather your party within 10' of the bag, drop the hole inside, and hold on as you are sucked through a gate into the Astral. The two items are destroyed in the process, but now you can get to any plane you want just by finding the right color pool. (Be sure you put the hole inside the bag, not the other way around, as that would cause the items to vanish without taking you along.)