A simple wizard for selecting or hiding scene objects based on layer.

LayerSelectWizard.cs

using UnityEngine;
using UnityEditor;
using System.Collections;
using System.Collections.Generic;

public class LayerSelectWizard : ScriptableWizard
{

    public LayerMask selectedLayers;

    [MenuItem("OffTheGrid/Wizards/Layer Select Wizard %l")]
    static void CreateWizard()
    {
        ScriptableWizard.DisplayWizard<LayerSelectWizard>("Layer Select Wizard", "Select", "Hide Other");
    }
    void OnWizardUpdate()
    {
        helpString = "Choose the layers to select or show.";
    }

    void OnWizardCreate()
    {
        List<GameObject> gameObjects = GetInLayer(selectedLayers);
        Selection.objects = gameObjects.ToArray();
    }

    void OnWizardOtherButton()
    {
        GameObject[] allObjects = Object.FindObjectsOfType<GameObject>();

        //Get our gameObjects
        List<GameObject> gameObjects = GetInLayer(selectedLayers);
        
        //Hide everything
        foreach (GameObject go in allObjects)
        {
            if (go.activeInHierarchy)
                go.SetActive(false);
        }

        //Reactive the ones we need.
        foreach (GameObject activeGo in gameObjects)
        {
            activeGo.SetActive(true);
        }

        ScriptableWizard.focusedWindow.Close();
    }

    private List<GameObject> GetInLayer (LayerMask mask){
        List<GameObject> gameObjects = new List<GameObject>();
        GameObject[] allObjects = (GameObject[])Resources.FindObjectsOfTypeAll(typeof(GameObject));
        foreach (GameObject go in allObjects)
        {
            if (mask.IsInLayerMask(go))
            {
                gameObjects.Add(go);
            }
        }
        return gameObjects;
    }

}

public static class LayerMaskExtensions
{
    public static bool IsInLayerMask(this LayerMask mask, int layer)
    {
        return ((mask.value & (1 << layer)) > 0);
    }

    public static bool IsInLayerMask(this LayerMask mask, GameObject obj)
    {
        return ((mask.value & (1 << obj.layer)) > 0);
    }
}