Pretty self explanatory, I just got Sims 3 (because I hate Sims 2. Sorry to all those fans of the Sims 2, lol) and I'm debating which expansion pack I should start out with.

On one hand, I'd love to get a La La Land themed Sims world going sometime, but I found a werewolf Sim download online that I absolutely love? I'm kind of a sucker for paranormal/horror themes '^^

My only question is how appropriate is Late Night? I have two little siblings and my parents are kind of strict on what they let us watch and play, so strip clubs and drunken bikini clad women are *probably* not the best thing to show up in this game?

As with Supernatural, I heard the zombies are really annoying?

Either way, both expansion packs are on sale for $5 on Steam, so I gotta make up my mind soon.

There are no strip clubs 😂 It's just they dance on tables (they are both equally inappropriate ik)

Late Night, for the simple reason that everything in the world is better than Supernatural. Supernatural really sucks. It's so much nothing in one pack. Really, it's the only EP I'd regret buying.

Late Night has nothing super inappropriate. Sims can dance on tables, but whatever they were wearing remains on their body. And Sims do not get 'drunk', they get 'juiced' which can alter their chosen traits to include things like Party Animal for as long as the Juiced moodlet remains, which is a few hours, I believe. The addition of celebrity system can be really annoying, because your Sim can easily be caught in a scandal for a lot of things - including having a child out of wedlock, which comes across as very old-fashioned and weird, given how most people in reality don't care if a celebrity had a kid out of wedlock.

You get Vampires, which are a sort of fun lifestate to play. You don't have to drink from Sims, your Sim can sustain themselves just fine on Plasma Juice as a Quick Meal from any fridge or you can plant Plasma Fruit, a new seed type that grows the fruit and can be eaten by Vampires. It can also be bought for, I think, 30 Simoleon each at the grocery store. You need Gardening at level 7 to plant that seed, though. Outside of that, Vampires have the advantage of learning skills much faster during night hours (from 6 PM onward) and are long-lived. Young Adult stage is 103 days or so.

Supernatural also gives you Vampires, though minus the Plasma Fruit. But you can still get Plasma Orange Juice from fridges. Supernatural also includes Vampiric Sunscreen elixirs and the Immortal lifetime reward, which makes it so your Vampire can be in sunlight (temporarily, or permanently with the lifetime reward) without being negatively affected. They do sparkle at this point, though... Outside of that, you also get the Werewolf, Fairy and Witch lifestates. Werewolves are great if you want to do a lot of hunting for gems, insects or similar. Downside, they will turn into werewolf when their mood is too low or when there is a full moon. Fairies can use their magic to boost needs or skill learning with certain auras, cast some magic on other Sims and can even repair things by turning tiny. Witches are faster at learning the new Alchemy skill and their potions sell for more at the Elixir shop. They can also cast magic with certain spells, from making fire to freezing something and more, the higher their level.

There's a new Alchemy skill, as said; a few new traits and more gothic/horror/fantasy themed clothes than in Late Night, which is more club-focused.
Yes, Zombies will appear every full moon, but you can easily find a mod on this very site to remove Zombies spawning entirely on full moon nights, so no need to worry about those, in that case.

I left out a bunch of stuff, but out of the two, I think I find Supernatural more fun because it adds more than just focusing on one aspect of Sims life.

Eh, depends. Late Night has musical instruments and bars (but also wimpy vampires). Supernatural - either you like occults in your game (and includes better vampires), or you don't.

I went ahead and bought both, lol XD

Supernatural is my favorite expansion but i would never pick it as a first expansion. So i would say Late Night

Late night? Too many new venues and not enough sims mean they're not populated.
Apartments are a pain. You can't really build to add to them.
Mixology? Maybe I need to play with that more, as I never saw the point.
Did they fix the problem with elevators getting stuck?

I donno... to me, witches and fairies is more interesting. I favor SN over LN.

There's a mod for that!

Anyways, I would suggest picking up both when you have the chance. Showtime is probably actually better for that La La Land feeling since the world it comes with is modelled after LA whereas Bridgeport has a more Seattle-ish feeling to it.

As mentioned above, Bridgeport has issues with too many venues + a weird subway system, so you will need some mods and rebuilding to get the right density of sims in your venues. I personally find Moonlight Falls mostly flavorless (too flat, too scattered out) but the expansion definitely brings a lot of new gameplay and objects.

And as always, there are mods to deal with the paparazzi and zombies.

Actually, I would also suggest getting Ambitions since it does come with a lot of everyday gameplay as well & ways of earning money outside the rabbitholes.

Uh, could you tell me where one would typically find that mod, so that I know where to avoid it and preserve my wholesomeness?

I've done my research on this, so if you don't mind, I'll correct you on this one.
The primary source of inspiration for Bridgeport was Pittsburgh, Pennsylvania. The rough shape of the main landmass and the downtown area clearly resemble Pittsburgh.
Since Bridgeport is, of course, a scaled-down, simplified depiction of an actual city, it's hard to pinpoint exactly what it would look like if it were a real city. But this is how I think of it. (warning: ramble)

Bridgeport is a very East Coast-looking city, with industrial roots and probably a revitalized urban appeal that struck down on the city during the late 20th century. I don't know if they had hipsters in the 80s and 90s, but for the purposes of this post, they did.

The city's central landmass is now one of North America's most bustling and inviting downtowns, with increasingly tall office towers that have attracted numerous large corporations and firms - HSBC, Philips, HalleyCambridge, PlumBank, Unilever, KMedia, and plenty others.
Gentrification has taken place on an unpresidented scale west of downtown; near, around and past the Port-District, the once run-down tenements of Gayle Haven are now ever so popular among millennials. Its recreational parks, free-minded attitudes, and the highly convenient el-train line make for a post-semimodernironic hipster artisanal craft beer and overpriced coffee dreamland.
The city also has the densest public transit network in Simania, offering 4 types of rail-based transit throughout the metropolitan area and a highly efficient bus network. Its two main airports, Bridgeport Wellinger Intl and Bridgeport City Airport, are located just 3.5 miles from each other.

Today, Bridgeport is considered the pinnacle "East Coast" cities in the Americas by many, and it's many diverse qualities and unique shopping destinations attract droves of tourists annually. Bridgeport is everything New York City would have been, had it been located as near the Atlantic Ocean as Bridgeport is. In some ways, it is the gateway to the Americas.
Perhaps one of Bridgeport's most peculiar features is the quaint upper-middle class neighborhood on its oceanside waterfront. The peaceful and unassuming neighborhood is home to several public figures, including actress Amber Parker, who now lives on the very same land first set foot on by European explorers four centuries ago.