I’ve written a blog post about my level building workflow, from using Tiled as the 2D tilemap editor to importing the tilemap in UE4 and using instanced static meshes to construct the level:
http://roll-playing-game.com/blog/2015/04/level-building-workflow-from-tiled-to-ue4/
http://roll-playing-game.com/blog/wp-content/uploads/2015/03/Example-Tilemap.png
http://roll-playing-game.com/blog/wp-content/uploads/2015/03/Example-Loaded-Tilemap.png