I will be quite honest, the giant overhaul mods scare the bejessus out of me. I messed around with them on and off for a while and I just can't get comfortable with the amount of stuff thrown at you. So, I would like to know of some really nice mods that are made for Vanilla.
Not sure what you mean as the huge majority of mods are made for vanilla. Are you looking for a lighter overhaul? If so, check out http://www.gamesas.com/index.php?/topic/1123328-tie-tamriel-immersion-experience/, which only uses vanilla resources. If you're looking for nice mods in general it would help to know more specifics.
I am also trying to find a mod to replace the leveling system in a SIMPLE way, not like Ngcd (way to complicated for me). I saw the +5 to attribute level up mod but I have also read lots of problems with it. If anyone could give me some feedback on this, I would be much obliged.
nGCD (and Realistic Leveling) are complex but not complicated for the user - one could say the opposite as they remove all micromanaging and do everything seemlessly in the background. They are quite easy to get up and running without worrying about settings - but you can customize them if you like. They require OBSE but so do lots of brilliant mods.
Never used the +5 mod but I doubt it is problematic. It has like millions of downloads and should be rather simple/safe I'd guess. Not 100% on this as I've never used it as said. Anyway, http://www.tesnexus.com/downloads/file.php?id=9914 is a safe alternative.
One last thing, I know of all the big lighting mods like Illumination Within and that stuff, but I can't remember this one mod I used that made things, how should I say it, "magical" in dungeons? Sort of darker but with more pronounced glows on gems and stones. If anyone could help a poor lost soul out it would be much appreciated.
Cheers!
All Natural Real Lights makes dungeons darker but also gives light to Varla and Welkynd stones. http://www.gamesas.com/index.php?/topic/1147846-relz-weather-all-natural-thread-31/ is excellent in itself as well, plus makes it possible to use http://www.gamesas.com/index.php?/topic/1156995-relz-wipz-immersive-interiors/.
Also, check out http://www.gamesas.com/index.php?/topic/1084754-relzanimated-window-lighting-system-thread-6/.