My locally modded lighting and tonemapping settings, fine tuned for vanilla temperate theme and a custom high contrast LUT. http://i.imgur.com/AJ54HWo.png

LightingRebalance.cs

using ICities;
using System;
using System.Reflection;
using UnityEngine;
namespace LightingRebalance
	{
	public class LightingRebalanceMod : LoadingExtensionBase, IUserMod
		{
		public string Name
			{
			get
				{
				return "Lighting Rebalance";
				}
			}
		public string Description
			{
			get
				{
				return "Rebalances lighting, tonemapping and daynight properties.";
				}
			}
		public override void OnLevelLoaded(LoadMode mode)
			{

			// light color gradients
			// time of day (midnight to midnight) in 0 - 1.0 floats

			// light from the sides (affects sides of buildings the most)
			typeof(DayNightProperties.AmbientColor).GetField("m_EquatorColor", BindingFlags.Instance | BindingFlags.NonPublic).SetValue(DayNightProperties.instance.m_AmbientColor, new Gradient
				{
					colorKeys = new GradientColorKey[]
					{
						new GradientColorKey(new Color32(19, 21, 26, 255), 0.24f),
						new GradientColorKey(new Color32(140, 143, 147, 255), 0.27f),

						new GradientColorKey(new Color32(160, 163, 167, 255), 0.4f),
						new GradientColorKey(new Color32(160, 163, 167, 255), 0.6f),

						new GradientColorKey(new Color32(120, 123, 132, 255), 0.74f),
						new GradientColorKey(new Color32(19, 21, 26, 255), 0.75f)
					},
					alphaKeys = new GradientAlphaKey[]
					{
						new GradientAlphaKey(1f, 0f),
						new GradientAlphaKey(1f, 1f)
					}
				});

			// light from below (affects road undersides)
			typeof(DayNightProperties.AmbientColor).GetField("m_GroundColor", BindingFlags.Instance | BindingFlags.NonPublic).SetValue(DayNightProperties.instance.m_AmbientColor, new Gradient
				{
					colorKeys = new GradientColorKey[]
					{
						new GradientColorKey(new Color32(20, 23, 27, 255), 0.24f),
						new GradientColorKey(new Color32(129, 131, 134, 255), 0.27f),

						new GradientColorKey(new Color32(130, 132, 136, 255), 0.4f),
						new GradientColorKey(new Color32(130, 132, 136, 255), 0.6f),

						new GradientColorKey(new Color32(130, 131, 132, 255), 0.74f),
						new GradientColorKey(new Color32(20, 23, 27, 255), 0.75f)
					},
					alphaKeys = new GradientAlphaKey[]
					{
						new GradientAlphaKey(1f, 0f),
						new GradientAlphaKey(1f, 1f)
					}
				});

			// light from the top (affects terrain and building roofs the most)
			typeof(DayNightProperties.AmbientColor).GetField("m_SkyColor", BindingFlags.Instance | BindingFlags.NonPublic).SetValue(DayNightProperties.instance.m_AmbientColor, new Gradient
				{
					colorKeys = new GradientColorKey[]
					{
						new GradientColorKey(new Color32(32, 36, 42, 255), 0.24f),
						new GradientColorKey(new Color32(165, 170, 175, 255), 0.27f),

						new GradientColorKey(new Color32(200, 203, 207, 255), 0.4f),
						new GradientColorKey(new Color32(200, 203, 207, 255), 0.6f),

						new GradientColorKey(new Color32(165, 168, 178, 255), 0.74f), 
						new GradientColorKey(new Color32(32, 36, 42, 255), 0.75f)
					},
					alphaKeys = new GradientAlphaKey[]
					{
						new GradientAlphaKey(1f, 0f),
						new GradientAlphaKey(1f, 1f)
					}
				});

			// directional light color (sun / moon)
			UnityEngine.Object.FindObjectOfType<DayNightProperties>().m_LightColor = new Gradient
				{
					colorKeys = new GradientColorKey[]
					{
						new GradientColorKey(new Color32(17, 20, 23, 255), 0.24f),
						new GradientColorKey(new Color32(159, 125, 99, 255), 0.27f),

						new GradientColorKey(new Color32(175, 170, 162, 255), 0.4f),
						new GradientColorKey(new Color32(175, 170, 162, 255), 0.6f),

						new GradientColorKey(new Color32(190, 150, 109, 255), 0.74f),
						new GradientColorKey(new Color32(17, 20, 23, 255), 0.75f),
					},
					alphaKeys = new GradientAlphaKey[]
					{
						new GradientAlphaKey(1f, 0f),
						new GradientAlphaKey(1f, 1f)
					}
				};

			// light intensities
			UnityEngine.Object.FindObjectOfType<DayNightProperties>().m_SunIntensity = 1.6f;	// sun / moon light
			UnityEngine.Object.FindObjectOfType<DayNightProperties>().m_Exposure = 1.6f;		// ambient light



			// tonemapping
			var toneMap = GameObject.Find("Main Camera").GetComponent<ColossalFramework.ToneMapping>();

			toneMap.m_Luminance=					 0.60f; // brightness but inverted
			toneMap.m_ToneMappingBoostFactor=		 0.90f; // brightness but more linear
			toneMap.m_ToneMappingGamma=				 3.20f; // gamma correction (midtone brightness)

			toneMap.m_ToneMappingParamsFilmic.A=	 0.60f; // brightness, affects midtones/highlights more
			toneMap.m_ToneMappingParamsFilmic.B=	 0.20f; // brightness, affects shadows more, lower values increase contrast, high values wash out
			toneMap.m_ToneMappingParamsFilmic.C=	 0.10f; // similar to B but more intense
			toneMap.m_ToneMappingParamsFilmic.D=	 0.75f; // affects shadows more, low values wash out, high values dark contrasty
			toneMap.m_ToneMappingParamsFilmic.E=	 0.01f; // black clipping, gets intense quickly, values over 0.29 unusable
			toneMap.m_ToneMappingParamsFilmic.F=	 0.35f; // lower values may increase contrast, higher may darken, intense interplay with E

			toneMap.m_ToneMappingParamsFilmic.W=	11.20f; // wash out at low values, not much change in general


			// daynight properties
			var daynight=UnityEngine.Object.FindObjectOfType<DayNightProperties>();

			daynight.m_Tonemapping=true;			// enables tonemapping for the sky, becomes less dull when true

			daynight.m_SunAnisotropyFactor=0.7f;		// affects light scattering around the sun
			daynight.m_SunSize=0.02f;				// sun size


			daynight.m_MieScattering=3f;			// light scattering around the sun, also affects fog somehow
			daynight.m_RayleighScattering=1.30f;		// affects color contrast between horizon and sky



			}
		}
	}