Here are some thoughts I shared with Zacchaeus already for the Alley maps in Waterdeep Dragon Heist. The map has a bunch of roof lines. Using terrain provides some interesting options for simulating hiding on the other side of a pitched roof. The GM may need to turn on and off roof terrain pieces during play to handle specific scenarios, but it gives some fun options.
Original map with walls drawn. No ability to get up on roofs. Players leaving the map would accidentally see to the other side.
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If you redo each major plane of the roof, you get some simulated 3D effects. Players can actually see much of the roof from the ground -- at least for roof lines that are facing them directly. Players can also climb up to a roof, bust through a basement window/door and enter buildings or fly up there.
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In play:
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These sort of scenarios are almost always going to fall to the person creating the adventure conversion and what they think makes the most sense. As a GM, you can always override the built in LOS by double-clicking to select LOS definitions you don't like and replacing them with something you prefer.