Hi, its my 1st post here so I might as well post my workflow from Sketchup to UE4.
Models by John Cedric.
Thanks to Youtube channel Sketchup to Unreal Engine I've succeeded (mostly) in importing assets from Sketchup to UE4.
Most of the objects are separated by groups and imported separately from Sketchup via .obj file. As of 4.10, UE4 own UV unwrap for lighting is pretty good for basic shapes.
For complex and higher poly object, I exported to Blender via .dae and unwrap all the UV, rearrange it and generate lightmap UV before exported to UE4 via .fbx.
Its kinda tedious, but I like to transform the free models (credited of course) into quick usable assets in UE4. They're all for strictly for personal usage.