UPDATE AND PSA: Many people have addressed that they won't be trying this mod out until it is closer to finalized. I have no issue with that, it is your game after all.
That said, I will not be providing updates or support for this mod, FOR THE TIME BEING, until I can get it much closer to a place that I feel is more deserving of its title and closer to a true FINAL version. This MAY include scaling ALL XP values, both for leveling and XP gains to something in-line with what D&D players would expect in a mod by this name.

There's no drama, no other reason, and I won't be taking down the existing versions of the mod in the meantime, I just want to focus on this particular mod until it is the very best that I can provide, so that future updates can be only very small tweaks and not complete overhauls of a single theme or file, like the last update. So, for now, if you are enjoying this mod, continue doing so, and if you are on the fence, I suggest waiting until the next iteration or just giving this a shot to see the way the mod FEELS (because that much seems pretty good to ME) and what I am going for.

FOR ADDITIONAL CREATURES NOT GIVING EXPERIENCE:
Use the Beta version in the Optional Files Section that integrates the additional values from the awesome Experience Mod Add-On by ArventeSeverin to cover MANY mods that the default Experience Mod misses. Due to the sheer volume of variables needed to alter, it will take some time before this version is out of beta and thoroughly tested, but if you really need to get that XP, the file is there for download.

Mod Description:

Personally, I think that the Experience mod may be my #1 must-have mod on my list, along with its Static Skill Leveling add-on (and the beautiful upgrade that makes it feel like it was always there), but it does have a few issues with it that feel really bad when playing...

First off, the values for just about everything are pretty generic by default, which I can't really fault the author for because of the sheer number of values needed to be taken into account, but I knew I immediately had to dial this in to something a little more... chaotic, but predictable.

Secondly, it is WAY too easy to level up early on, especially if you are like me and like to use a lot of mods that add map markers (like Atlas), which leads to this sharp falloff of ALL XP as you rapidly out-level everything in the area. It can also trigger some mods (Sinister Seven, I'm looking right at you) so early, that you are completely unprepared for higher-level foes and are simply doomed.

Lastly, I really didn't like that all quests are created equal, in terms of experience gained. Why?! There are some important things going on in the world, and should those important, if arduous tasks, not be more rewarding than taking Arcadia a few herbs?

So, I changed, tweaked, tested, reverted, cried, started over, and eventually found a sort of method to tweaking and testing in a way that completely breaks my save from all the loading and saving... but it is worth it... and will continue to do so until I am happy with the state of everything that the base mod has to offer.

Now, coming from a long-time D&D player, I always felt like leveling in Skyrim was too fast to begin with and Experience cranks it up to 11 in the early levels with some of the mods I mentioned. So, I tweaked everything according to one simple notion: "How important is this, REALLY, in the grand scheme of things?"

Some mentions of the changes made:

- The Main Quests are worth quite a bit more than anything else, and the Dragonborn Questline really only trails behind it by a small amount, because it is kind of a continuation of the main quest in a way.

- Quest-lines that are really niche got a nerf to their gained XP, based on just HOW niche they are. Examples: The Companions give less for each part of their quests, since not everyone wants to deal with that, but the hit is really marginal in the grand scheme of things, as they aren't exactly evil. The Thieves Guild took a harder hit because not everyone wants to steal or rob people and there are plenty of material rewards waiting for you there. The Dark Brotherhood (sorry brothers and sisters) took a huge hit, with you having to be a murderer to even start the quest... however, I love this quest line and between the loot, the story, and Shadowmere, it has plenty of rewards already.

- Discovering locations gives some really odd numbered XP, but that is just me going with the "being chaotic" method. However, you will start to see a sort of method to my madness after a while. Places with a probability of having high-level creatures (IE- Dragon Nests, Giant Camps) will give a decent little boost. Capitals give more than towns, shoppes even less, etc.

- Some of the races gave some super-low XP, giving only 1 or 2 XP, but just cranking up the numbers was the WRONG answer. They have been slowly and methodically dialed into place for some creatures that can be real killers in the early game, but kind of push-overs later on (ahem... chaurus)... so They are at an XP value now where early on, they might be worth the risk of taking on early for that smidge more XP needed to level (...or maybe not, your call).

- Reading Books is slightly more beneficial, but first hand, real-world experience will be even more so.

- Currently, all special actors give a semi-randomized amount of experience, with the exception of named Bosses. Other ones, like Bandit Chiefs and such, that are not unique bosses, will give a decent XP boost, but maybe it doesn't always seem proportionate to the difficulty. This isn't totally intentional, but I haven't dug too deeply into the experience ESP to suss out all of the nuances... yet...

I am sure I am leaving some things out here, but you should be getting the gist of what I have done here, and will continue to do later on.

Currently, these settings seem to be able to get you through the first 5 levels or so at a decent clip, but then you will start to see a little bit of a slow-down, and it begins to taper off to a mild plateau at the mid-20's to low 30's and eventually becomes a bit of a grind after level 38... and a real grind at level 45.
I feel like this is really in line with the game, personally. Even with difficulty mods, combat mods, and extra monsters, most things after level 50 are a novelty at best, and really aren't providing so much of a challenge, but more of a resource-sink of some kind.

And, that brings me to the end and why I called this D&D XP...
As I said, I have been playing D&D for over 35 years (since I was 8) and, well, in most every D&D game I have ever played for a long time, there is always a plateau in XP progression that hits between levels 8 to 10 (of a max of 20 in current iterations, and level 12 was considered "high level" in AD&D back in middle school).
Sure, you keep gaining XP, but the amount of XP you need to get to advance goes up exponentially with each level you gain. And that is what this feels like. You are already more powerful than pretty much every resident of Skyrim by level 50. Every level after that is you taking another step towards near-godhood... which *should* be slow and earned.