Yamazaki also has a somewhat “unnatural” - but very useful if you´re going for Silent Assassin - sniping point from the courtyard, near one of the side doors. You can set her up to go have a smoke outside and shoot her from there, with the guards not noticing the body.
The best sniping method for Soders is arguably just to snipe his heart from the other side of the morgue (yes, it counts for Sniper Assassin)
Hawke´s Bay has basically the entire beach providing a great view of Alma´s room (sure, it´s not an elevated position, but still). Miami has plenty of spots for Sierra (never tried much with Robert tbh, will have to). In WC, you can use some of the attic/room windows for Janus (don´t remember Cassidy).