I'm actually working on it this weekend. Here's a few of the things I'll be exploring:
Note: I say exploring because I can't be 100% sure it will make it into the final set of changes.
I'll likely be looking at the profitability of most businesses/residences/community buildings, and adjusting it to fit the fact players have significantly more energy, which gives them a larger daily income.
The level 1-10 community buildings will probably be adjusted to be on 24 hour collection timers, since it looks like it's being abused a bit more than expected.
The rest of the community buildings that are made with parts will be evaluated as well. It's likely some of the higher level ones will have their part counts reduced.
Industries and Goods production will definitely get some attention, as higher level players just can't produce enough goods to keep their businesses supplied. If this gets boosted at the higher end, expect prices of items to go up significantly to account for it.
Item Levels as a whole will be looked at, and balanced against the level range of the majority of the playerbase. Some buildings will be available for the 50+ players, but likely a lot less than what's currently there.
Quests as a whole will probably be changed a lot. This is largely due to the way the game plays now with all the extra energy. This will be done to hopefully accommodate new players and to ensure their first session of the game is enjoyable, and that they come back for more.
I'll see if I can boost the amount of neighbors that you can visit/tip.
Gifting could use some love. If this requires engineering work though, I'll probably not be able to do much.
Expansions are probably bit too punishing. I'll see if I can get their requirements to be a bit more sensible.
That Jewelry store idea is fantastic. I'll see what I can do about making something like that a reality in some capacity. There's a few possible ways it could be done, but definitely don't expect this to be something anytime soon