Photo subjects are a non-cooperative four year old daughter and cityscapes (I live in Chicago, so lots of good architecture...
I'd recommend the 85mm f/1.8 for the 'non-cooperative four year old daughter' - I had one of those (the 85/1.8, that is) and I've got one of those (the non-cooperative four year old daughter, that is). I swapped the 85/1.8 for the 85mm f/1.2
L II, and although that's a great lens, the slow AF makes it a challenge with a child who won't hold still. The 85/1.8 focus much faster.
Many of the responses are suggestions for landscapes, but...the OP mentiones cityscapes specifically. The prime lenses of choice for shooting architecture are the TS-E lenses (PC-E in Nikonland). The shift feature enables you correct for the perspective distortion you'd normally get by pointing the camera up at a tall building. The tilt feature is also great for landscapes, as you have complete control over depth of field.
Here are a couple of samples with the 5DII and TS-E 24mm f/3.5
L II:

EOS 5D Mark II, TS-E 24mm f/3.5
L II, 1/60 s, f/11, ISO 100, +10 shift

EOS 5D Mark II, TS-E 24mm f/3.5
L II, 1/2 s, f/8, ISO 100, +12 shift