I haven't had much time to play Skyrim lately, sorry for the delay in updating the OP.
Skyrim update 1.6 is out very soon, I'm sure a lot of you are testing the beta already. Mounted combat and, more importantly, fixed navmeshes, are sure to bring a lot of mods that will enhance the game even further. That brings us to what I was looking into lately.
I've got a bunch of ini tweaks that might be useful for most players, especially in combination with some mods. These will be added this weekend so you can try them out and give me some feedback on whether they make any difference.
Fixed navmeshes mean that mods like Open Cities Skyrim will finally work without the usual bugs (like NPCs being where they shouldn't be).
I've always intended this guide to be brief but comprehensive, answering all basic questions that new players might ask and having a list of more significant mods that improve the gameplay without altering the vanilla feel of the game (unless it seems necessary). It should also be a collective work so if you have any suggestions to add, feel free to do so.
What prevented me from further improving on the guide I have was saves corruption. That's right, once you install, uninstall and reinstall a variety of mods, you're bound to encounter not only conflicts but also save breaking "features" that will be a PITA to resolve in the future. That's the way Elder Scrolls games' engine works and I don't think there's any simple solution to it.
I'm trying out some lore-friendly mods that will increase immersion of the game, some might alter the combat a little, others can add things like portable campsites, wearable lanterns, etc.
There is a large ongoing project that aims at improving Skyrim experience (STEP) and, in my opinion, largely succeeds in that matter, but the drawback is that it's very time consuming and the amount of mods may not be easy to manage, especially to people who are new to modding.
The major graphical overhauls brought by the latest ENB releases can alter the visuals in a significant way. Last time I checked, ENB had a truly awful impact on performance but it might have changed so I will look into that very soon.
EDIT: also, mods like Better Sorting and CFM will become obsolete in the near future, Script Dragon will no longer be required and PISE is now developed as ASIS from scratch.
There are some less known mods such as Economics of Skyrim that might bring changes to aspects of the game that had previously been untouched by modders.
Unofficial Skyrim Patch should contain a lot of fixes done by other mods until now, but with the amount of things it fixes, the development is kind of slow.
Optimising textures is a crucial feature that improves performance and reduces VRAM consumption.