Vacations - I really just need them to allow me to use the calendar to pencil in that my sims are taking a vacation from this day to that day. Also allow me to to make certain lots into vacation lots b.c I turned part of Oasis Springs into Rome, Africa, Egypt and India. I don't really need them to give me a pack with those places since I am slowly turning different lots into different parts of the world, I just need the ability to tell my sims they are going on vacation to this lot I set up for them, and for the lot to be tagged as a vacation spot that workers need to show up to.
Business - While I would like more careers, I would prefer they just enhanced the ones we had. Mob wife for example sounds ridiculous and funny, having a police officer actually chasing my criminal sim if they find out their job, my sims job NOT just being some rabbit hole that tells me of their exciting time at work, trying to keep my criminal life, or secret agent life secret. It would add more depth for me instead of just adding more careers that are just rabbit holes, or poorly executed jobs that leave you wanting more.
Occult - I am a sucker for a lot of fantasy things, but my thoughts for this would be to expand on the already existing ones we have. Some sims should be afraid of vampires. I once used a vampire to lock the door at a small gathering to allow him to drink everyone's blood forcefully. Not one sim was afraid, no screaming or cowering or trying to run for their lives. I could only assume Werewolves would have the same issue. I do secretly think it would be cool if a werewolf could turn from human/werewolf into a larger, but controllable pet though. Mermaids are sadly lack luster, no underwater experience, no learning skills, they can't lure sims into the ocean to devour them, they don't try to hide their mermaid secret, if I wasn't such a sucker for mermaid tails I wouldn't even play them as they are not any different from being a human. I feel fairies would suffer the same fate. Instead of making like seasonal, or elemental fairies who live along humans secretly, they would only be floating wing wearing humans who appear at every social event like its normal.
Something New - like adding depth to the already existing game play? Yes I'd like that. Secret agents who actually keep their jobs a secret? Serial romantics who flirt way too often with my sim. Occult creatures who keep their existence secret. Sims who genuinely are afraid of occult creatures. The ability to plan a family vacation on my calendar. Mermaids that are not just humans with a hydration meter. Making more jobs interactive. Allowing secrecy in the game, allowing consequences in game, make stealing someones husband/wife way harder, make marring a non-committal WAY harder. Give these new features an ON/OFF switch in game settings like the aging is. Name the new pack: "Get Depth" and make the CAS a bunch of culturally diverse styles like braids, kimonos, Hanbok's, toga, etc.
It'll never happen though. xD