So I just installed ETaC and love it because it makes the towns more usable without adding a bunch of clutter. Is there a good City mod for the interior of the five major cities that just lightly improves them by making them more useful (like adding smelters to Riften and Solitude, adding a smelter to the Skyforge) and other minor improvements without adding a bunch of clutter? Something that is lighter in its approach than JK Skyrim?

My suggestions would be

http://www.nexusmods.com/skyrim/mods/8793/?

https://steamcommunity.com/sharedfiles/filedetails/?id=165603966

latter is by the same author, but Workshop only for some reason. Adds smelters to Riften, Riverwood, Solitude as well some tactfully placed trees shrubs and other minor clutter that blends in quite nicely. Understated is probably the best word to describe it.