Check out a useful pack for level design in Unreal Engine. 

Check out Level Design Tool for Unreal Engine that will speed up your creation process and save you time on CTRL-clicking on multiple actors when moving or grouping up. The toolkit allows you to "put a box or sphere around a zone and with a click of a button select everything within that zone." You can also hide or unhide meshes, select static meshes or actors by a tag or name, plus use construction blueprints to place meshes along a spline path or attach multiple actors to a dummy actor.

The pack features 13 blueprints, 1 editor utility widget, 1 data table, 1 struct, 2 enum, 26 materials, and 52 material instances, plus a demo level.

Features:

• Select static meshes and or actors with 1 click of a button
• Hide and unhide a lot of static meshes and or actors in your scene
• Search by using a tag or by simply entering the name of the static mesh and or actor in the name section
• Blueprint interaction system (button, bridge, door, elevator, POI, and teleporters)
• Spline-based mesh placer
• Straight-line mesh placer
• Line of sight tool (useful for shooter games)
• More

You can learn more and get the toolkit here.