^For the downtown shot:
You don't need a remote- You can set a timer and just let it go.
Check out your tripod. A 30 second exposure can be messed up by even the smallest movement. That means if you have a cheaper plastic tripod (or even a cheaper aluminum tripod), you'll need to try and weigh it down to make it more stable. If you can help it, don't walk around your tripod as well. It seems farfetched, but vibrations in the ground can affect long exposures. Wind is also a common culprit, as already mentioned.
Don't go too small on the aperture- you might find that sharpness takes a hit due to diffraction. Here's an article on it:
Understanding Lens Diffraction
I don't think hyperfocal distance will help with something that far away, but there's that as well (and a ton of free phone apps to help you).