So I've begun looking into the cleanest and most non-intrusive city expansion mods to bring the capitals to life without being too obviously altered. Basically I'm just looking for city enhancements that only use vanilla/DLC content and are properly cleaned with TES5Edit or have clear instructions within BOSS to do so. So far I think I'll be using Dawn of Whiterun and either Better Riften of Riften - Thief Edition. I'd be delighted to hear any recommendations for the rest of the capitals, but specifically I'd like to improve the atmosphere of the rest of the closed cities (Solitude, Markarth, and Windhelm). Either way, any response is greatly appreciated.

Have you seen this thread? http://www.gamesas.com/topic/1474451-expanded-cities-and-town-or-immersive-settlements/ I know that Solitude is mentioned there.