After I finish the clothing mod I'm working on I intend to work on a gameplay overhaul that requires all the DLC and, among other things, closes holes between the DLC and places level requirements on them so they have to be spread out and done in a certain order.
For example:
DLC1 - Level 10
DLC2 - Level 20
DLC3 - Level 30
DLC4 - Level 40

Here's the problem though. I've never actually done the DLCs myself yet, and I was tossing around the idea of only allowing the use of VATS after you start Old World Blues and become a cyborg, thereby necessitating it to be the first DLC available.
The reason is, I hate the Pipboy with the burning hatred of hell itself, and use the Readius to turn it into a handheld device. With this (and to a lesser extent with the normal Pipboy, really) the logic behind VATS doesn't make any sense. So I wanted to make it an aspect of your inevitable cybernetic implants, possibly even renaming it to CATS in-game (Cybernetic Assisted Targeting System). On top of fixing the logic of it and being generally much cooler, it'd give you room to learn your character for a while without VATS as a crutch, which I've personally been very guilty of.
Now I know that Old World Blues is actually the 3rd DLC, and I don't know if doing it first would create any sort of continuity issues in the stories and dialogue of the DLCs that follow it. Anyone know?

The only DLC that needs to be done in order is Lonesome Road which is always last. Old World Blues could actually be good as either the first or second DLC, there are some notes and dialogue that tell you about some of the characters in Dead Money when they were in Big Mountain(before the events of Dead Money).

Honest hearts is the easiest and should probably be first since it doesn't directly tie into any of the other DLCs.

Dead Money should be third since its definitely the hardest, VATS is incredibly helpful and has some high skill checks. The recommended level for Dead Money is 15 IIRC, but level 30 sounds like a safer idea.

Lonesome Road needs to be done last, the story demands it. The best time to do it is probably a few missions before the battle of Hoover Dam, story wise.

Cool, thank you. I'd heard that Old World Blues might reference characters from previous DLCs and that's what had me most concerned, but if it really is just talking about what they did there before any of the DLCs took place then that's perfectly fine. Finding such things would have completely different yet both completely valid kinds of enjoyment depending on whether you've met those characters already or will later.

I agree with THE LOBOTOMITE! After i played OWB I wondered why it wasn't released first. It explains a lot of the things you see in the Sierra Madre.

I think it's better that way. Seriously, when you play Dead Money you say 'Who the [censored] would make something like this?'. I think it adds to the horror of Big Mountain when you see just how many terrible things were born in that place. I think Elijah was accurate in calling it 'A place filled with old world misery'. (Or maybe it was Ulysses?)

I'm pretty sure Elijah called it "A scientific graveyard of old world misery" but Ulysses probably mentioned something about old world misery too. He likes talking about old world misery.

The Sierra Madre is pretty much the Post-Apocalyptic equivalent of the Taj Mahal.

The reason why it is such a hell is because everything that could have possibly gone wrong, went wrong.

The construction workers cut corners in creating the Villa,
Frederick Sinclair did not have enough time to restore the Vault to its original purpose, after making it a trap
The cloud that was used to preserve the casino got let loose
And the Gala Event happened RIGHT on schedule. The second the great war happened. So, the Security Holograms went everywhere, and instead of a security broadcast, there was a wide invitation to it, even after the war.

Talk about bad luck and timing.

Don't forget that Sinclair decided to get stuff from Big Mountain. So he got steak knives that can cut steel easily, a ventilation system that is rigged with a dangerous chemical weapon, and hazmat suits that won't come off, and restrict communication. The Sierra Madre would be very different if Big MT hadn't sent them the Cloud and the Hazmat suits.

and the holograms.