That said, the particular issue I would have especially with 1a would be how it would interface with the waterfront... basically it would be a 30 foot or so drop to the water, which might be good for Global Warming, but it would be a pretty far drop to make any River/Harbor Walk work out.
Chicago has a couple projects in the works that do exactly that, with plazas decked over rail/railyards that step down to a water level river walk; 150 North Riverside and 444 West Lake(River Pointe).It could be the harbor "cliff" walk.
Here's the before:
Current(150N Riverside on left and River Pointe on right):
Both Chicago parcels have somewhat more solid ground to work with than parcels 1a+b, but still necessitated dramatic cantilevers. The River Pointe project addresses the river walk poorly imho, giving it a lovely blank beige wall as a backdrop. The 150N Riverside river walk will be much more activated.
Draw what inspiration ye may from these projects.