I've been looking at this thread for a long time now and I love some of the thoughts in here. I have a few of my own which, hopefully, with time I will try to hash out and make more presentable. For now though I'll just say a few quick ones that I might end up working on more:
Rebuild:
Old Rideau Canoe Club (at the end of Fifth at the Canal by the Lily Pond) (designed by Moses Edey (Cattle Castle, Daly Building)
Lansdowne Wooden Entrance Archway (by the previously metioned Club)
Old Lansdowne Coliseum (in one form or another)
Ordnance Building (opposite Commissariat Building (Bytown Museum))
Rideau Club Building (or something else, just please fill in that empty space across from Parliament)
Regrets:
Not lining Parliament up. If you move the Parliament Buildings 37.5m ENE along the same axis as Wellington everything lines up. Peace Tower=Metcalfe, Mackenzie Tower=O'Connor, Confederation Building Peak=Bank, Supreme Court=Kent. Arghh.
Not lining the War Memorial up. Either expand Elgin all the way or don't (and line the Memorial up with old Elgin), but don't go half way.
The suburbs.
Damming the falls.
Not following through on some of the Capital Plans (especially Greber).
Letting the Queensway become a big massive block of concrete through the city.
Hope to be back with more.