Roofs can be challenging, but clipping is your friend and so are “guide rails”.

Here is a curved front for a building that then goes straight back.
https://steamcommunity.com/sharedfiles/filedetails/?id=2592204989

Standing on top you can see the clipping looks pretty smooth. I was able to do this with the wood beams curving back with the roof. While the left most roof pieces are connected to the building, the next roof pieces are connected to the wood beams curving back, acting as a guide to curve the roof pieces. There are also other pieces here and there to fill in gaps.
https://steamcommunity.com/sharedfiles/filedetails/?id=2592205033

This does cause a lot of ugly looking clipping inside though, but you can cover it with the small floor pieces. You can see the guide rails here again, but with a flat part now, which is the small floor pieces covering all the clipping, giving it an overall much cleaner look.
https://steamcommunity.com/sharedfiles/filedetails/?id=2592205079

I try to avoid “free place” and all of these are snapped in. Not only is there a lot of clipping you can do, but you can (not always) snap multiple pieces to a single snap point.
https://steamcommunity.com/sharedfiles/filedetails/?id=2592205105

For our teleport area, I went with a double helix pathway and dioramas. Each reflects something about that area.
https://steamcommunity.com/sharedfiles/filedetails/?id=2592205136

And who doesn’t have a cliff base?
https://steamcommunity.com/sharedfiles/filedetails/?id=2592205466