I've been thinking about ideas for mods that would drastically enhance gameplay and such, and my main idea is "more locales for World Adventures". Unless we were to rip apart and reprogram the game (which, depending on the game in question, is anywhere from simple pimple to a herculean feat of computer-deity-level skill/nigh impossible without hacking the company in question and learning their secrets), I'm just unsure as to what's even possible with Sims 3. I know with Sims 2, it's pretty limited, mostly to objects, interactions, careers and majors, and tuning, but just what is possible to mod into Sims 3? Is my idea of having more worlds in WA impossible due to hard-coding, or would it be very much possible to send my sims to a fully-functional custom-made Italy, complete with unique quests, people, songs, cuisine, and all that?

You can travel to any world you want with Nraas Traveler. In other words: It has already been done =)

While basic world traveling has indeed been done, what I'm referring to is a fully-custom and fully-functional vacation world. Traveling to other worlds with Nraas Traveler simply results in the world being treated as any other base world, not as a specially-made vacation world, like with Egypt, China, or France.

Maybe you can create one using create a world?? you can then maybe create a special NRaas traveller module to treat it as a vacation world??? idk honestly. But if you create a vacation looking world using CAW with base camp and resorts then it can probably be seen as a vacation world by the user.
I'm a newb when it comes to modding so don't have much knowledge of how it can be done.

I should also note that I'm also quite the noob at modding, and have no intention of even trying to learn.

Ok this is the part I missed^^
Well you already can modify the people living there, I always prepare my travel worlds in another save than copy the nhd over..

Arsil has made a custom hidden Japanese Trait, take a look at that if you want to make your own nationalities. You can connect it to the custom song, although that means you have to record one in Simlish^^
There are lots of custom recipes around, but it could be difficult to restrict them to a certain world, I unlocked all recipes for my homeworld anyway, because globalisation.
I don't like the quests much, which is why I never tried out the adventure's board in an Nraas traveler's world, so i don't know which type of quests it gives.. The easiest way would be to make your own board for every custom world and make it give out unique quests.
I am very sure that can all be done, it depends on how good your programming knowledge is and how much you are willing to learn for this. Have fun =)

Then why did you post in the Creator's forum?

Because this place is a damn maze. Also, I do have SOME modding experience, but hardly any to be taking on requests, or making something of this magnitude.

At least it didn't end up in Site Issues. To be fair, if the question had been asked in Discussion someone would have suggested this as a better spot to ask. The suggestion would have been wrong in this instance, but it would have been made.