Level Design - placement andworkflow

I’ve thought about this but never quite got what the best solution is:
When designing a level I what to re-use the assets as much as can so I can optimize performance and possibly reduce 3d design efforts. To this extent when building architecture elements like houses I can make a few types of walls, windows and doors, mix-and-match and produce some variation while keeping a coherent theme (level kits). These elements are modeled as separated meshes and placed on the editor. When building the walls the place where a windows or doors would be are already predefined. The placement part of is what kinda annoys me, while in 3d software tools (Blender, 3dsMax) I can easily snap vertexes and edges there seems to be no such option in Unreal. It’s bad enough when thing are kinda aligned with axes but when the meshes are rotated it is much more difficult. Maybe it is a small problem but I was wondering what is your workflow to make this easily, more accurate and less of a game of guessing the right position?

You can use standard units in the editor so that your dimensions will snap to the grid. But if you want to, you can also build your level in 3ds Max and export to UE4 using the FBX Scene Import option which will match the object positions and instances