1) Vacation Homes anywhere. If I want to live in Sulani, but take a long Winter Vacation for the Holidays in Willow Creek ... I'd need a Vacation Home there to do that. Let us set 1 or 2 lots as a Vacation Home in each "city".
2) A new Lot Trait: Forbidding Aura. Residents are immune, but suffer an initial negative friendliness penalty when meeting new people. Random Visitors would be extremely rare, and they'd get an uncomfortable / tense moodlet for coming, especially uninvited ... The Creepy House on the Hill vibe. (Unless they have the Loner and / or Gloomy Traits). "Oh, a Wicked Vampire lives there, let's go introduce ourselves and interrupt his dinner".
3) When new things are added, previous packs should be updated to include the new additions. I.E. Why doesn't the spell Scrubaroo work on the trash in Sulani? (Yes, I know Sulani came out before Magic, but it still should effect it. Butlers / Maids / Gardeners not taking care of Meat Walls, Insect Farms, and Composting from the upgraded toilets? That's part of Gardening / House care.
4) Blacklist and Whitelist CAS Clothing and Traits. (And stop with the Kleptomaniac Paparazzi). Some of the generated Sims are dressed horribly, and usually have 2 out of 3 traits the "negative ones". Nothing like a bunch of Paranoid, Kleptomaniac, Evil Sims looking like they are dressed in every odd pieces of clothing they own.
5) Private Schools and School Uniforms! I miss schmoozing the Headmaster / Headmistress to get the kids into private schools.
6) Be able to disable the Club Dance styles introduced in Get Together. The Group dances are fine, but I miss being able to "just dance" with the original dances (except for the kneading dough move). Possibly just add a "Just Dance" option.
7) Slow Dance. Sometimes, I'd like my Sim to actually dance with their partner / date.
Edit to Add:
8) Lock Gate from Paparazzi. If I have a fenced in yard, I'd like to be able to lock the Paparazzi out of the yard.