What to expect
The size of the stones catches your attention first. Then look at how the blocks meet: that is where the construction becomes especially interesting. You do not need to finish a whole list of other ruins to give Sacsayhuamán a worthwhile place in your trip.
How it fits into a journey
Give it its own part of a day alongside a quieter city programme. Add Q'enqo or Tambomachay deliberately, asking how long each stop receives.