Going back to some original plans here:
https://www.calgary.ca/Transportatio...ions_final.pdf
I think option E is a pretty good one. I might suggest elevating it from the bluff to 20th ave instead of underground. Something like the Vancouver skytrian here:
https://goo.gl/maps/u6QBvMqjeXu6vVLs7
where it isn't all that intrusive, and if I had to guess, might even bee cheaper than integrating it at grade on Centre and tunnelling under 16th ave which I suspect has loads of utilities.