I mostly tend to play vanilla. But I do have a few mods.
GreenWaterFix. Not sure if it was ever officially fixed... but I do like being able to see clearly underwater. So I keep it installed.
Shrouded Armor Enchantments. This one is purely for aesthitic reasons. This allows me to disenchant the Shrouded Hand Wraps and apply them to necklace/boots/rings of my choosing.
Nightingale Elven Crafted Silver Mail(nocape version) Basically this one is... well I'm more or less of a perv. Changes the female worn Nightingale into something a tad more sexier. I got the mod above simply so I didn't have to switc between Nightingale gloves and shrouded.
No Helmet Mod. Basically makes every helm in the game invisible. Except for Shrouded Cowl and a few others. Of course you can choose which helms you want to see or don't see.
I also tried out Bigger Whiterun. This mod makes Whiterun larger. Well more like a bit more cramped. It adds several vendors, a few new houses, a Statue of Ysgramor, and a few walkways on top of the walls. Also get a few new NPCs to marry and some kids, including a Dark Elf kid. Also adds more plant life. I would have kept the mod installed but unfortunately my computer couldn't quite handle it. With Dawnguard there is that chance of a Vampire attacks and if everyone in the city started to freak out all at once my game crashed. Then again I did sorta kill someone right in the middle of a crowd.
The one slight thing I don't like about the mod was that the market place was a bit cramped. Not necessarily a bad thing. But wasn't exactly what i'd have liked. I believe they are, or at least were, planning to do this to other cities but I haven't looked into it much.
Oh and a White Mini Dress mod... yup. Pervert.